Hello, and welcome to today's London mayoral live blog.

This morning at 9am LBC radio is hosting the first broadcast mayoral debate of the campaign. Tory Boris Johnson, Labour's Ken Livingstone, Lib Dem Brian Paddick and Green Jenny Jones will be going head to head in the studio, and my colleague Hélène Mulholland will be with them, and reporting live for this blog. You can listen to the debate live here.

After that, from 1pm-2pm we'll be debating transport in the capital, with special guests:

• Tony Travers, London expert at the London School of Economics.

• Caroline Pidgeon, chair of the London assembly transport committee and the Lib Dems' deputy mayoral candidate.

• Rachel Holdsworth of the Londonist, a website about the capital.

• Annie Mole of the Going Underground blog.

Post your questions for our guests below.

Since the post of elected mayor of London was introduced in 2000, transport has been one of its key election battlegrounds. Transport for London is one of the four main bodies the mayor controls, and is responsible for running the Underground, Overground, Docklands Light Railway, trams, buses, roads and cycling (which we discussed separately earlier).

Here's a video filmed by my colleagues Oliver Laughland and Alice Salfield in which Londoners explain the transport issues that matter to them.

So far in the campaign three transport issues have played a major role: fares, the role of unions and driverless trains, and airport capacity.

Fares

Ken Livingstone has made transport fares one of the key issues of the election, promising to cut them by 7% this year and freeze them in 2013. From 2014 they would not rise above inflation. Figures released by the House of Commons library in January showed the average transport fare in London had risen 26% since 2008, when Boris Johnson was elected, with bus fares up 50%.

Johnson is committed to yearly increases of the inflation rate plus 2%, although the popularity of Livingstone's pledge – a recent YouGov poll found 82% of respondents supported it – seems to have spooked him. In the press release launching his policy on driverless trains last week Johnson promised to "hold fares down", giving no further detail.

At the same time he has aggressively characterised Livingstone's fare cut plan as representing a £1.2bn cut in investment, using strikingly Labourite language:

The choice at this election is between investment in our transport system - or cuts in investment at the worst possible time.

Livingstone defended his proposals against such accusations to my colleague Andrew Sparrow in January. His key point was that "in a budget of £8bn if you can't find the money to have a 7% fares cut, you are breathtakingly incompetent". And he rejected a Channel 4 FactCheck analysis that there was no surplus that could be drawn upon to pay for the fares cut. A February 2012 Transport for London board paper highlighted by Livingstone last week (see page one, paragraph two) showed a total £338m surplus in Transport for London's operating budget. Livingstone puts the cost of his fare cut at £270m for the first year.

Livingstone has also posted a video featuring comedian Eddie Izzard explaining his fare cut policy. It is a lot better than a previous one featuring Stephen Pound MP.

Unions/driverless trains

Last week Johnson launched his transport policies with an eye-catching pledge to introduce driverless trains on the London Underground within a decade, something he partly justified on the ground that the move would "reduce the bargaining power of the union bosses intent on bringing London to a halt".

Livingstone said that the non-driving staff who would work on these trains instead ("train captains") would still be able to strike. "In other words it doesn't solve the issue of industrial disputes, which is what seems to motivate this convoluted policy from the Tories."

There have been far more tube strikes during Johnson's four years in power than Livingstone's eight. Reaching a no-strike deal with the unions was one of the promises Johnson admitted not being able to keep in his recent assessment of his own record in so far. He is lobbying the government to change strike laws to mandate a minimum turnout of 50% in strike ballots.

Livingstone is essentially promising to return to his former policy of "negotiating with the workforce", which saw, as he put it recently, "the number of shifts on the tube lost due to strike action ... cut by 98%."

Brian Paddick, the Lib Dem candidate, has also hit out at the transport unions, saying: "Londoners need a mayor who will stand up to the unions, not by refusing to meet them until the eleventh hour but by engaging with them, looking the likes of Bob Crow in the eye and being tough but fair with them."

Airports

Johnson has proposed a new private-sector funded airport to the east of London, nicknamed "Boris Island", something the government announced in this year's budget it would now consult on. He says this would increase prosperity and the number of jobs in the capital and contribute to the regeneration of east London, while its noise levels would be low because flight paths would be over the Thames Estuary and the North Sea.

By contrast he is firmly opposed to the building of a third runway at Heathrow, saying this would be an "environmental disaster" and promising "it will not be built as long as I am mayor".

Livingstone has said he thinks an a new airport in the Thames Estuary would be "devastating for west London and threaten 114,000 jobs", and would end up downgrading Heathrow "to a regional feeder airport". He calls for investment in high-speed rail as an alternative to air travel, and the construction of two further phases of Crossrail. If more airport capacity is needed "and there is no other alternative", Livingstone says other airports outside London, for example Stansted, should be expanded instead.

Boris Johnson and transport

Johnson's most visible move as mayor has been the introduction of the cycle hire scheme, first proposed by Livingstone but now completely identified with Johnson to the extent that the cycles are known as "Boris bikes". (We discussed this earlier.) He has overseen improvements to the above-ground local train services (the "Overground"), introduced the Oyster card on national rail services, and made the Freedom Pass for older people valid 24 hours a day. He took "bendy buses" out of service, introducing instead a handful of dramatic new vehicles styled after the popular old Routemaster buses; he says 600 of these will be in service by the end of his second term, each costing no more than "an existing hybrid bus". One of his first policies was to ban drinking on public transport; protest parties on the Underground took place on the last night alcohol was allowed, but the ban now seems widely observed. He scrapped the western extension to the congestion charge and got rid of Livingstone's proposed £25 charge for the most polluting cars.

Johnson pledges to reduce tube delays by 30% by 2015 (Transport for London says delays are already down 40% since 2007-08), to continue construction of the Crossrail east-west rail link and the extensions to the Docklands Light Railway in the east and the Overground – linking it up in the south as an "orbital" railway by late this year – as well as expanding the cycle hire scheme east and west and "exploring expansion" to the south.

He wants to introduce a new code of conduct for 11-16-year-olds who have free travel, launch a strategic review of London's road networks, including a £50bn "congestion-busting fund" to tackle black spots, and continue to upgrade various tube lines in order to increase capacity. He also promises to construct a new tunnel from Greenwich to Silvertown and to "examine the feasibility" of a new pedestrian bridge between Vauxhall and Chelsea bridges.

Both Johnson and Livingstone have proposed that the mayor takes control of National Rail services within London, and both have proposed returning the age older people can get the Freedom Pass to 60.

Ken Livingstone

Livingstone's most high profile and radical policy as mayor concerned transport: the congestion charge for vehicles entering the city centre. During his time in office, he oversaw a modernisation of the transport system, especially the bus network, and introduced the Oyster pre-pay travelcard. A two-tier payment system evolved, with fares for those using Oyster kept relatively low while cash fares increased hugely, in a move which targeted tourists instead of locals and pushed more people into the arms of the quicker Oyster system.

Livingstone today says he would not bring back the western extension to the congestion charge or allow drinking on public transport again, and announced in his "transport manifesto" (read the full document here) that he would not bring back the £25 a day "gas guzzler" charge for the most polluting vehicles either, saying that would be too expensive to implement.

He would leave in place the existing eight new Routemasters introduced by Johnson, "but we are not buying any more, not at £1.3m each", he told the Guardian in January (that price had risen to £2m each by the time his transport manifesto was published – see Johnson's view of their price above).

Livingstone also promises to "start preparatory work" on a cross-river tram scheme originally planned to run from Camden in the north, across Waterloo Bridge, to Peckham and Brixton in the south, which was cancelled by Johnson in 2008 due to lack of funding.

The Labour candidate also says he would roll out the cycle hire scheme "far more widely", mentioning south London, altering it so it was "a far less expensive scheme". He says he would review the contract with Barclays – which he calls "the cheapest sponsorship deal ever" – and would require sponsors to make the scheme more attractive to a wider range of Londoners. Staying with cycling, he would review major junctions, trial a cyclists-only green traffic light phase, redesign the cycle superhighways, expand the "Greenways" cycle routes, extend the Freedom Pass to allow older people to use the cycle hire scheme for free, and work with boroughs for consistent cycle lanes across the capital.

He promises better bus services in the suburbs, and says he will "get a grip" on tube delays, freeze the congestion charge for the full four years of his term, and "build the case" for Crossrail 2 and the South London line to Victoria, and extensions to the Docklands Light Railway and Croydon tram. He would make a third of all tube stations accessible to those who can't use steps by 2016, start a campaign for more courtesy on public transport, including trialling "keep your feet off" designs on buses, introduce a system to allow drivers to get information on their phones about where the nearest parking spaces are, campaign for rickshaws to be banned, and link up pedestrianised spaces in central London so people can walk in a pleasant environment from Bank to Oxford Street.

Livingstone would also campaign against the proposed route of High Speed 2, and for a route "that doesn't demolish hundreds of London homes". And "if it is not too late by May" he would negotiate with the International Olympic Committee to ensure the maximum possible access for black cabs to the Olympic Route Network. Livingstone says he will announce plans to cut air pollution separately at a later date. His campaign has also focused heavily on the 7% fare cut discussed above.

Brian Paddick

The Lib Dem candidate calls for a one-hour bus ticket, and discounted fares before 7.30am. In a Q&A with Guardian readers he said "the congestion charge doesn't work and the cycle hire scheme is costing millions of pounds in subsidy because it's badly managed". He added: "I want all but those who have no choice to use public transport or cycle." He also raised the prospect of pedestrianising Oxford Street, with just one "shuttle bus" going along it, and said he was "absolutely committed to making London's roads safer for all road users particularly cyclists and pedestrians" and wanted to "enthusiastically pursue" the Love London, Go Dutch approach which aims to make the capital's streets as cycle- and pedestrian-friendly as Holland's.

Jenny Jones

Green party candidate Jenny Jones says £1bn a year could be raised for public transport from a London-wide pay-as-you-go road-pricing scheme and pledges to "research" this idea. She suggests new roads and river crossings should only be for public transport, cycling and walking, and cyclists and pedestrians should have priority at traffic lights. She also wants a 20mph limit on residential streets, plus faster and safer cycle paths, the layout of dangerous junctions changed, and the cycle hire scheme expanded. She calls for a "very low emission zone" in central London and wants to make all buses "low emission hybrids or better" by 2016. Jones says that if elected she would increase the congestion charge to £15 for ordinary vehicles and £40 for "gas guzzlers". And she promises to create a fund to help taxi drivers clean up their vehicles, and to clamp down on illegal mincabs.

Post your questions for Tony Travers, Caroline Pidgeon, Rachel Holdsworth and Annie Mole – or simply debate the issues – below.

Hélène Mulholland writes:

Hélène Mulholland writes:

The hustings is about to start. Each of the four candidates will each have a minute to state their case. The running order will be decided by the throwing of a coloured dart (party colours) at a dartboard in the studio. Whoever gets closest to the bullseye will go first.

Each of the candidates was just given one minute to summarise their key policies. Hélène Mulholland writes:

Boris gets the bullseye so he goes first and outlines his nine-point plan for London. Jenny goes second and highlights her policies, including making streets safer for walking and cycling and cleaning London's dirty air. Ken goes next, saying we are in difficult times and we need to help Londoners. He wants to put some of the high fares back in people's pockets. He highlights the benefits of his planned 7% fare cut, plus his pledge to return the educational maintenance allowance for students.



(LBC present this as someone having a one-minute tube journey with doors opening and closing on cue.) Paddick goes last, highlighting his police experience to ask Londoners who they want to keep Londoners safe. He also highlights his targeted fare cuts.

A caller asks about putting more police on the streets. Boris Johnson says crime has gone down and "you can bet your life" that he will be continue to put more police on the streets.

He says it is not true that there are fewer police on the streets than when Ken Livingstone left office.

Livingstone disputes this.

"It is nonsense to say crime is coming down," he adds.

Nick Ferrari, the presenter, says crime has gone down 10.8% overall.

Johnson says crime is 11% down.

Hélène Mulholland writes:

Boris says crime has gone down under his watch, and there are more 1,000 police officers on the beat. Asked by Ferrari if there are fewer police on the beat now than when Ken was mayor, Boris says his figure is that there is 32,573. Ken when he became mayor they had 25,500 and they got the figure up to 32,000. He disputes Boris's claim that crime is down. Ferrari says but it is (down 10.8% overall) but not in every crime category. Paddick says Boris has cut the number of sergeants in safer neighbourhood teams by half. Boris insists there are 1,000 more warranted officers than when he came to office. Jenny Jones, who served on the now defunct Metropolitan Police Authority, says a lot of them are not on the streets but doing back-office jobs because of cuts in that area. Ken says vacant posts are not being filled, which is demoralising for those left behind. Boris has defended what he has been able to do against the backdrop of massive cuts to resources.

Hélène Mulholland writes:

The issue of where Boris was when the riots hit London last summer comes up during a question from the next caller. Paddick asks the caller, Carl, about how he felt about the fact that Boris didn't rush back when it happened (he was on holiday in Canada but eventually came back). The caller says it didn't bother him that Boris didn't rush back. Ken then wades in to criticise Boris for not offering an immediate presence and giving Londoners reassurance. Ken also criticises heavy handed policing. Paddick mentiones the need to reform stop and search powers that see far more black Londoners stopped than their white counterparts A caller asks Ken about the use of his credit card (this is in reference to the Daily Mail spread I mentioned earlier). Ken says he was in office for eight years so the amounts are not high. Yes but why did you need to buy six bottles of cognac, asks Boris. Jenny then asks Boris why he has spent £5,000 on taxi fares during his term, despite saying he was going to bear down on waste.

Hélène Mulholland writes:

Paddick asks why senior Met police officers have chauffeur-driven cars and grace-and-favour residences. Boris says he has talked to the Met chief, Bernard Hogan-Howe, about these excesses. He also points out that through cutting waste and efficiencies he has been able to freeze the council tax for four years. It's getting a bit heated on all sides.

Hélène Mulholland writes:

A question on cycling safety from a listener who had an accident and injured himself. Jenny says there should be a default 20-mile speed limit across the capital. She wants cycling measures at junctions, though she doesn't specify what she wants. Paddick says there is an obsession in the city with the speed of traffic, whereas the need is for greater safety. Boris says he's working on it. Now you are, exclaims Paddick, because the Lib Dems on the London assembly have been going on about it and there's an election looming. Boris says we need investment in the capital's infrastructure to improve cycling and "that guy" (Ken) wants to undermine that (through his fare cut). Ken claims police are investigating Transport for London for corporate manslaughter over the death of two cyclists. He adds that Boris's transport adviser Kulveer Ranger said traffic flow was the priority. Strong stuff.

Hélène Mulholland writes:

Ken is asked whether he would extend the congestion charge if elected. (He introduced it in his first term, extended to the west in his second term, then Boris scrapped the western extension when he took power.) Ken says he isn't planning to, and takes a swipe at Boris over his cable car project, and the cost of it. Boris defends it. Jenny agrees with Ken that it's not worth spending more money on reinstating the western extension of the congestion charge. She highlights the very unsung issue of poor air quality in the capital. She wants to see a £40 charge slapped on gas guzzling cars. Ken says you won't solve congestion by more charging, but by having control over the utilities who constantly dig up London's roads. If you charged them £1,000 a day, they'd be more swift in filling the holes. (We've had a bit of silence because the volume faded out in the room where the media is sitting.) Ken is asked about a £40 charge for gas guzzlers. He says there will be no increase in the congestion charge, or council tax. Boris presses Ken on his pledge to cut fares by 7%. He admits it would cost over a billion pounds over four years, but he says it's £253m this year. He insists this can be funded from a massive surplus - ie because there is more fare revenue than was anticipated. There are separate budgets, he stresses. Jones wades in about the new Routemaster bus, which cost a lot to develop. The second bus only came out yesterday - three weeks late. Ferrari says they'll return to buses later.

Hélène Mulholland writes:

A question on gay marriage. Paddick, who is in a civil partnership, says couples gay or straight should be able to get married. Ken says: "We all agree with Brian." Turning to the tube unions, Ken says strikes went down on his watch, whereas Boris hasn't even met the union leaders. Ken says if he had been mayor, he would have secured a four-year deal right at the start of his mayoralty. Now, the unions have got the power because the Olympics are around the corner. Boris has had 22 strikes on his watch. Boris says he "won't give ground" on strikes in the Olympics. Jenny reminds Boris that he failed to meet his 2008 promise to secure a no-strike deal, but worse still he never did anything to make it happen. Paddick says Boris's claim not to give ground won't make things any better. You have to get around the negotiating table. Paddick says he hears Bob Crow, the RMT leader, is quite a reasonable guy. Jenny says Crow is a really nice bloke. Ken says that Boris had promised to keep a ticket office open at every station. That didn't happen. In some stations there is no ticket office, and female commuters going home late at night feel unsafe. Boris says he kept a ticket office at every station that has a ticket office. Paddick says whatever Boris says, women do not feel safe later at night. Paddick suggests buses dropping women off at the end of their streets. Boris says he's in favour of that.

The presenter, Nick Ferrari, just read out a "Twitter poll" showing that so far 25% of respondents are backing Livingstone, 25% Johnson, 16% Jones and 8% Paddick.

Hélène Mulholland writes:

A question on housing from a listener who says he and his partner are thinking of splitting up because they'd be better off living apart on practical grounds. They have four children. Ken accuses Boris of failing to deliver sufficient affordable homes. Boris says he has built over 50,000 in his first term. He says he met his target, but he is challenged on his definition of affordable - they're not all for people on very low incomes. On airport capacity, Boris has made the case for a new airport hub to the east of London and he says London needs it for business. Jenny says his idea is "barking mad" and is never going to happen. Aviation is a dangerous commodity in a world facing the threats of climate change, she says. Paddick says it's about switching slots, so that the flights for business are concentrated. You can get more flight capacity out of the existing infrastructure, he says. Ken is generally opposed to increased flight capacity, and points out short-haul trips to France and Belgium can be made by train.

Hélène Mulholland writes:

A question to Ken on his tax arrangements. Ken says he is not avoiding tax; he pays the proper rate of tax on the income he takes home, he says. Paddick tells him the way he has chosen to arrange his payments, which go into a company, means he is not paying as much as he should. Paddick also says that Boris is going to benefit significantly from the abolition of the top rate of tax (just from his mayoral salary and Telegraph column he's on £400,000). Boris will not discuss his tax affairs, but says he's paying the right rate of tax. Ken points out that Boris had a company called "Finland Station". Boris said he once set up a production company, but he says he's never set up a company to channel his income payments.

Ferrari announces the final results of the "Twitter poll", which are a bit of a surprise. Brian Paddick is now on 24%, Ken Livingstone is also on 24%, Boris Johnson is on 16%, and Jenny Jones is on 8%.

Hélène Mulholland writes:

A listener whose son was mugged calls in, so it's back to policing. Paddick says officers need to be out on the street in uniform. The police and the community need to stand side by side against the criminals. Jenny agrees it's about visibility. It's absolutely crucial that the police are trusted. The candidates wrap up with a quick summary of their pitches. Boris Johnson highlights his plans for jobs, and says Ken's fares pledge would cut investment for transport. Jenny Jones says she wants to see a more equality in the capital and says more attention needs to be paid to the environment. She urges voters to think of voting Green not just for her, but also for the London assembly (she's on the list too). Brian Paddick also urges voters to back Lib Dem assembly members on 3 May. Ken Livingstone says his fares cut would put money back into the pockets of Londoners. He will fight to the death to protect the freedom pass for older londoners, he says. That's it. I'm going to go and chat to the candidates and file back.

Simon Harris of ITV's London Tonight has just tweeted that Boris and Ken had a bit of a bust-up after the debate.

Johnson and Livingstone are involved in a furious row in the lift after the LBC broadcast. @londontonight — Simon Harris (@simonharrisitv) April 3, 2012

Sources say Johnson and Livingstone"nose to nose". Johnson 's face "red with rage" @londontonight — Simon Harris (@simonharrisitv) April 3, 2012

Boris Johnson called Ken Livingstone a "fucking liar" three times after the hustings, Hélène Mulholland reports.

We've learned that things did not go well in the lift after the hustings was over. Boris went nose to nose with Ken in a small lift and told Ken three times: "You're a fucking liar, you're a fucking liar, you're a fucking liar." Paddick and Jenny were also squeezed in, alongside LBC's managing editor, James Rea. Johnson's anger was due to claims made during the hustings by Livingstone about Johnson's tax arrangements, which the mayor flatly denies. He told me later that Ken's claims were "nonsense". Of course at that point we hadn't heard about the ding-dong in the lift.

Hélène Mulholland writes to say that she has not been able to contact Boris Johnson yet about the lift row, but Ken Livingstone's team has confirmed that Johnson said "you are a fucking liar" to Livingstone.

During the debate Livingstone said that Johnson had the same arrangements for declaring his income for tax purposes as Livingstone has, but Johnson says this is absolutely untrue.

When I spoke to Boris afterwards, he seemed calm. He said what he hoped he got across in the hustings was that London needs another four years of cost-effective responsible government. I also caught up with Ken. He said Johnson's company, Finland Station, was set up to handle his outside income from filming. "That's the same as my company - Silveta Ltd. That's not to avoid tax. If you really want to avoid tax you have something offshore." He said he enjoyed the hustings "immensely".

Johnson's campaign have issued a statement rebutting Livingstone's claims about the mayor's tax arrangements. The statement says: "His claims against Boris Johnson's tax arrangement are lies and he knows they are."

Johnson added:

In relation to my business affairs and tax arrangements, specifically do I have any company or other arrangements constructed to enable me to pay less tax and do I, as has been claimed by the Labour mayoral candidate and the opposition leader, have the same arrangements as Labour's mayoral candidate, the answer is simple and unequivocal in both cases: no.

He went on to say that his salary as mayor "is taxed as an employee of the GLA [Greater London Authority], in the same way as when I was an MP my salary was taxed as an employee".

He added:

Any other income that I have received from outside endeavours has been received on a self-employed basis, to me as an individual (no company or other structure has been involved). No income earned by me has ever been paid to a "service" company, through which a person or person's freelance earnings can be channelled so that they pay corporation rather than income tax. To suggest otherwise is a complete and utter fabrication.

My colleague Luke Martin talked to Jenny Jones, the Green candidate, to see how she felt the hustings had gone. She said there was a "lot of testosterone in the room" and "getting my voice in wasn't always easy. But she hoped that once the candidates' manifestos were published in full, the debate would turn away from personality to the policies candidates were proposing to implement to

help Londoners.

Ken Livingstone's team has just sent this statement regarding the lift row. It doesn't address the issue of whether or not Johnson's tax arrangements are the same as Livingstone's. A spokesman for Livingstone said:

Boris Johnson lost his temper because he lost the debate - he talked about cable cars not cutting fares and the squeeze on Londoners.

The Press Association's report on what Johnson said to Livingstone differs slightly from ours. PA claims Boris said: "It's all fucking lies, it's all fucking lies."

Either way I think we get the point.

Twitter is agog about the prospect of Ken and Boris going head to head. This comment perhaps sums up the mood:

Now I like Ken Livingstone, and I like Boris Johnson, but which is better?There's only one way to find out... #kenandboris #fight — Will West (@Castmana1) April 3, 2012

Meanwhile, Tony Travers of the LSE, Lib Dem deputy mayoral candidate Caroline Pidgeon, Rachel Holdsworth of the Londonist and Annie Mole of the Going Underground blog will all be online here on this blog at 1pm to debate transport in the capital.

In my opening post this morning I ran through all the key transport issues in the campaign, including fares, unions, driverless trains, and airports. I also ran through the main transport policies of each of the four main candidates. Click here to read that.

Here are some questions to get the debate going.

For Tony Travers, London expert at the LSE: Ken Livingstone says he can pay for his 7% fare cut out of Transport for London's operating surplus. Boris Johnson says there is no such surplus. Who do you think is right?

For Caroline Pidgeon, Lib Dem deputy mayoral candidate: Brian Paddick, the Lib Dem candidate for mayor, has said "the congestion charge doesn't work and the cycle hire scheme is costing millions of pounds in subsidy because it's badly managed". Can you explain exactly how the Lib Dems would rework each scheme?

For Rachel Holdsworth of the Londonist: If the cycle hire scheme is costing taxpayers a lot to run and seemingly being used mainly by a well-off section of society, is it worthwhile expanding it?

For Annie Mole of Going Underground: Boris Johnson wants to construct a new tunnel from Greenwich to Silvertown and to "examine the feasibility" of a new pedestrian bridge between Vauxhall and Chelsea bridges. Ken Livingstone promises to "start preparatory work" on a cross-river tram scheme originally planned to run from Camden in the north, across Waterloo Bridge, to Peckham and Brixton in the south and says he will "build the case" for Crossrail 2 and the South London line to Victoria, and extensions to the Docklands Light Railway and Croydon tram. Do we need all these extra lines and new projects?

And a question for all our guests: both Livingstone and Johnson have proposed that the next mayor takes control of National Rail services within London. What would be the advantages and disadvantages of such a move?

More on the Boris v Ken row, from my colleague Andrew Sparrow. Ken Livingstone has now challenged Johnson to answer three questions about his private company, Finland Station, if Johnson wants to prove that his tax arrangements were quite unlike Livingstone's. Here are the questions.

1. Did [Johnson] pay income tax on all of his earnings from Finland Station? Can he categorically say that he didn't receive any income through dividends and instead pay capital gains tax of 18% (rather than paying income tax at 40%)? 2. When he sold his shareholdings in Finland Station to David Jeffcock and Barnaby Spurrier - did he pay income tax on the money that he received at 40%, or capital gains tax at 18%? 3) Did he employ anyone?



I'll let you know when we get an answer from the Johnson camp.

Our panel debating transport policy in London have begun answering your questions. Caroline Pidgeon, the chair of the London assembly transport committee and Lib Dem deputy mayoral candidate, sets out some of her policies:

We would like to transform central London streets, pedestrianising large parts from Trafalgar Square up to Oxford Street and develop a New York-style "summer streets" programme as well as improving signage for walking. We do support expanding trams in London, starting with extending the Croydon Tram and the cross-river tram from Peckham and Brixton to Euston.

Caroline Pidgeon answers my questions about how the Lib Dems would rework the congestion charge and the cycle hire scheme:

We would improve the congestion charge by introducing variable charges throughout the day to discourage road use during the most congested hours. We would also increase the charge to keep pace with the rise in fares on public transport. On the cycle hire scheme, we would make the scheme easier to use for casual users, with a "one-swipe" facility; expand it south and north; increase the membership fee to non-Londoners; bring in tough penalties for the contractor to improve bike distribution; promote the scheme more widely and put the fun back in with limited edition bikes to celebrate events such as the Diamond Jubilee and Pride, funded by sponsorship.

Annie Mole of Going Underground responds to my colleague James Walsh's question about Boris Johnson having "taken credit for tube upgrade work that was already scheduled before he became mayor, while allowing the future upgrade program to slip worryingly":

Many of the tube upgrades were in place before Boris came into power and Boris has had the task of simply seeing a number of these through. The Guardian's Dave Hill also has a summary of Boris's transport record over the past three years and also agrees that he's simply "carried on where his predecessor has left off". I too would be interested to hear about Brian's plans for tube fares as we have the highest public transport fares in Europe (for the distance travelled) and fares appear to rise each year with little discernible improvements to the service.

Rachel Holdsworth of the Londonist answers my question about whether taxpayers should subsidise the cycle hire scheme if it is predominately being used by a well-off section of society.

The cycle hire scheme is worth expanding - but there's a number of caveats. - I think some of the expansion is to the wrong areas and won't combat the idea that it's a rich boy's toy. Taking it east to Tower Hamlets was good, but Boris's planned expansion out to Bromley, Richmond, Kingston etc seems a little odd as it skips over entire boroughs. What about Peckham, Lewisham, Greenwich, Brent? - The cycle hire isn't going to get casual users from outside zone one cycling into work without serious improvements to road safety - in reality and perception. - The system is still not perfect - it would be a better idea to get it running more smoothly before expanding further. - The scheme's funding is a problem. We were originally promised it would be all privately funded but that's not happened at all. The Paris Velib scheme is financed entirely by JCDecaux in exchange for revenue from previously city-owned advertising space (so you can argue there's a cost to the taxpayer there). But the deal with Barclays is ludicrously low, with "up to" £50m coming in until 2018, so TfL and the boroughs are having to stump up the rest. But, we have it, it's a fantastic scheme when it works, and to keep it to zone one really does keep it for the City boys and tourists.

Brian Paddick, the Lib Dem mayoral candidate, has commented on the Boris-Ken lift row. A spokesman for Paddick said:

Boris Johnson and Ken Livingstone clearly hold each other in complete contempt. This should be about Londoners, not the foul mouths and fragile egos of Boris and Ken. Londoners deserve better and it's time for a change.

From linvoy4england:

How is each candidate looking to manage the ridiculous year on year increase in fare prices across London?

Annie Mole replies:

This is an excellent question Isaac and I'd also like to know how the fares will be realistically tackled. Yes we need upgrades as we are largely using a Victorian system which is seriously unable to cope with current levels of commuters - that's not even thinking about the 3 million extra passenger journeys over the Olympics. Ken says he can pay for his 7% fare cut out of TfL's operating surplus. Boris says there isn't a surplus. Why don't TfL actually explain whether there is or isn't a surplus?

Rachel Holdsworth responds:

I'd love to see that as well. The TfL budget is a complicated thing and to settle this fight - and it does look like being the major fight of the campaign (lifts not withstanding) - it would be so useful if TfL could just explain how much money is earmarked for which project and where it's coming from. Presumably that would nip the rows about various budgets and surpluses in the bud.

From drygoni:

Personally I think the main issue is a disregard for road safety and the highway code. Both cyclists and drivers now regularly fail to indicate or signal when on the roads. I don't know what can be done about it apart from introduce cycling proficiency and stricter penalties for drivers breaking the highway code. Personally, I really, really like the 1930s approach of Model Traffic Areas for children so that they can learn the ways of the road in playgrounds and have fun at the same time. Obviously back then the highway code hadn't been around for very long so probably wouldn't work so well today. Unfortunately only one was ever built (Tottenham) But it is currently being renovated. More information here: http://untitledfruit.com/2012/03/01/model-traffic-area/

Caroline Pidgeon responds:

Road safety is a really serious issue. We need to make sure that our roads are safe for every user, including pedestrians and cyclists who are often overlooked. Did you know that there are 347 crossings in London that are unsafe for visually impaired people? This is an outrage in 2012, when London should be at its most accessible in preparation for the games.

My colleagues Hélène Mulholland and Luke Martin have just published their story on the Boris v Ken lift row.

They write that on arrival at LBC's studios this morning Johnson "made to hand his coat to Livingstone, as if mistaking him for a member of staff, to the amusement of some". Hélène and Luke add:

Johnson's aides released a letter dated 12 March from the mayor's personal accountant, Robert Maples, stating that Johnson is "liable to income tax on the entirety of his earnings and has made all due payments. He is not party to any tax avoidance or deferral schemes, nor has any of his income been transferred to any other members of his family."

Tony Travers of the LSE has joined the debate below the line, and he starts by stating that "there is little doubt" that Ken Livingstone's proposed 7% fare cut could be paid for out of Transport for London's budget. He writes:

Apologies for starting a bit late in joining this debate. I suppose the big transport question posed by the policies put forward by Boris and Ken is whether or not people would prefer a fare cut now rather than increased investment in the future. Ken is proposing a 7% fare cut if he wins the election and there is little doubt - given the large amounts of money sitting within TfL's £10bn budget - that such a cut could be delivered. However, every pound spent on a fare cut is removed from TfL's capacity to invest in improvements in an Underground system that desperately needs every penny it can get. So the real challenge begged by the difference between the candidates on this issue is: do we want short-term fare cuts or higher long-term investment? That, as Hamlet didn't quite say, is the question ...

Rachel Holdworth answers my question on the advantages and disadvantages of the mayor taking control of National Rail services:

As a resident of Lewisham who uses Southeastern, I cannot wait for National Rail to come under TfL's authority. The Overground is fantastic; clean, reliable, frequent. Southeastern is the exact opposite. The one pause it does give me is fares: it currently costs £3 peak / £2.10 off peak to travel from zone 3 to zone 1 on a Southeastern train. On the Overground it costs £3.10 peak / £2.60 off peak to travel zone 3 to zone 1 (I just did some quick and dirty checks with TfL's single fare finder). I suspect fares would go up if the franchises came under TfL.

Tony Travers answers Hannah Waldram's comment about what the top transport priority for the next mayor should be:

I think that by far the top priority should be to get the Underground running effectively - that is with fewer delays. While the buses are important, they are less susceptible to the kind of top-down intervention the tube requires. Since the (wretched and subsequently failed) PPP began - at Gordon Brown's insistence - in 2003, upwards of £12bn has been spent on reinvesting in the Underground. I am not sure that it feels as if £12bn+ worth of value has been added ... So I would do whatever necessary to drive up the operational standard of the Underground. Also support the idea (which Boris and Ken are agreed about) to allow the mayor to take over the "local" national rail system in London.

Tony Travers adds more about why he feels the mayor should take control of National Rail services in the capital:

I think the train operating companies and Network Rail are too far from any kind of accountability. Whatever one thinks about Boris, Ken, Brian, Jenny, Siobhan and the rest of the candidates, we do know who they are and they would be held to account for poor services, unstaffed stations etc in parts of London (mostly south of the river) where the tube doesn't reach. It would undoubtedly make it easier for people to comment on services and demand improvements if TfL ran (even if using the same companies) them rather than the anonymous organisations that are currently responsible.

Ken Livingstone's team has just put out another statement about this morning's debate. Their tack now is to claim that Livingstone concentrated on the issues that mattered to Londoners while Johnson is obsessed by the past. Here's the full statement from a spokesperson for Livingstone:

Ken Livingstone won this debate - by talking about things that really matter to people, like living standards and the need to cut fares and addressing the reality of life for millions of Londoners. By contrast the incumbent Conservative Boris Johnson was obsessed with arguments from the last election, raking over old stories now well by their sell-by date and going on about cable cars and other projects of no interest to the majority. As an incumbent who has built a brand based on being upbeat, his campaign's relentless negatives on Ken Livingstone are damaging to the carefully constructed Boris Johnson image. Unlike four years ago the Tory candidate is now subject to real scrutiny by the other candidates - and his touchy reactions indicate that as an establishment figure he is not used to it.

Thanks a lot to the panel – Tony Travers of the LSE, Lib Dem deputy mayoral candidate Caroline Pidgeon, Rachel Holdsworth of the Londonist and Annie Mole of the Going Underground blog – for all their contributions, and thank you for all your questions.

Here is a summary of today's events so far.

• Boris Johnson has angrily confronted Ken Livingstone over claims made by the Labour candidate in a radio debate that the Tory candidate's tax arrangements were the same as his own, which have been criticised. Johnson reportedly told Livingstone in a lift after the debate: "You're a fucking liar, you're a fucking liar, you're a fucking liar."

• Livingstone has been criticised for paying money he received from media engagements into a limited company, making him liable for corporation tax of 20% rather than an income tax of up to 50%. Livingstone said the money was used to pay people he employed and he made no financial gain by the arrangement. Although perfectly legal, the move has left him open to accusations of hypocrisy because he has attacked tax avoidance by others. In today's debate on LBC radio he was asked about this, and turned his fire on Johnson, claiming that his setting up of a company called Finland Station was just the same. Johnson has flatly denied this, saying: "Do I have any company or other arrangements constructed to enable me to pay less tax? … No … No income earned by me has ever been paid to a 'service' company, through which a person or person's freelance earnings can be channelled so that they pay corporation rather than income tax." A statement from his accountant seemed to back this up. In response Livingstone put out a statement asking Johnson three specific questions relating to whether he paid income tax on his earnings.

• In a Guardian Q&A on transport, London expert Tony Travers of the London School of Economics seemed to back up Livingstone's claims that he can pay for his planned 7% cut in transport fares through Transport for London's operating surplus. Travers said: "There is little doubt - given the large amounts of money sitting within TfL's £10bn budget - that such a cut could be delivered." However, he also stressed that "every pound spent on a fare cut is removed from TfL's capacity to invest in improvements" – which is the point Johnson has repeatedly made. The feasibility of the fare cut has been one of the most keenly debated policies of the campaign so far, and it came up in this morning's hustings too.

Thanks for all your comments and thanks again to our guests. Next Wednesday we'll be debating the economy, business and the City, with these special guests:

• David Dewhurst of Occupy London.

• Siobhan Benita, independent candidate for mayor of London.

• Louise Cooper of financial services company BGC Partners.