David Cameron's Downing Street was accused of a blatant cover-up last night over failed plans to crack down on Uber.

The ex-PM and George Osborne allegedly told aides to lobby Boris Johnson against curbs on the online taxi firm.

The Daily Mail revealed on Saturday that a No 10 adviser swapped emails with senior staff working for the then London mayor.

The ex-PM and George Osborne allegedly told aides to lobby Boris Johnson against curbs on the online taxi firm

Yet last night it emerged that Downing Street had failed to divulge details of the alleged lobbying operation when asked to do so under freedom of information laws.

Officials insisted – a year ago – there were no records of any exchanges. This later proved untrue when Transport for London officials released details of the correspondence.

Calls were made yesterday for an inquiry over both the alleged cover-up and the Government's links to the US taxi firm.

Opposition politicians pointed out that Rachel Whetstone, a senior vice-president at Uber, is a personal friend of both Mr Cameron and Mr Osborne.

'This blatant cover-up by 10 Downing Street must now lead to a formal inquiry,' said Caroline Pidgeon, the Lib Dem chairman of the London Assembly's transport committee.

Labour MP Wes Streeting also called for Theresa May to launch a probe into the issue. 'It is pretty clear that, in contrast to the openness and transparency of Transport for London, that Downing Street under David Cameron tried to cover up its cosy relationship with Uber,' he said.

'Under David Cameron, Downing Street was clearly acting as the lobbying arm for Uber which is extraordinary.'

When Mr Johnson was mayor of London in September 2015 he threatened to curtail the activities of Uber, a smartphone app that allows users to hail a minicab.

There were fears the web giant was putting traditional taxis out of business and contributing to congestion, air pollution, illegal parking and accidents.

Police figures also showed that rape or assault claims were being made about Uber's London drivers at a rate of one every 11 days.

Last night it emerged that Downing Street had failed to divulge details of the alleged lobbying operation

Mr Johnson wanted to force all drivers to pass a written English test. He also wanted to force all private hire firms to wait at least five minutes before accepting a booking and picking up a customer.

In response, Uber launched a petition, claiming that Mr Johnson's 'bureaucratic' proposals would make it harder and more expensive to travel around London. Within hours of the petition being launched, the mayor and senior aides began to be sent messages from Downing Street. Even Mr Cameron and George Osborne were understood to have sent texts to the mayor's mobile phone.

Daniel Korski, the deputy head of Mr Cameron's policy unit, was assigned to 'lead' talks between the mayor and his senior staff.

Email exchanges released by Transport for London under freedom of information laws, and revealed by the Mail on Saturday, showed how he offered alternative proposals on how to deal with congestion and pollution. Last night, it emerged that Mr Cameron's former assistant private secretary, Nicholas Howard, had also been asked for details of any email exchanges between Mr Korski, and either TfL or the Mayor of London's office.

But when Mr Howard responded a month later, in March 2016, he said only: 'We do not hold information in relation to your request.'

Mr Korski had in fact exchanged at least seven emails regarding proposed Uber legislation with both TfL officials and senior mayoral staff.

Labour MP Wes Streeting also called for Theresa May to launch a probe into the issue

Last night a No 10 spokesman said: 'Any suggestion of a cover-up is categorically untrue. Anyone who is dissatisfied with an FoI response is advised that they have the right to request an internal review about its handling.' However no further explanation was provided.

Mr Korski said he had no knowledge of the freedom of information request and had no input into No 10's misleading response to it. He also denied lobbying on behalf of Uber, saying the idea was 'fanciful'. He added: 'The idea that I acted inappropriately because of a relationship between the then PM and Rachel Whestone is even more absurd.'

But Steve McNamara of the Licensed Taxi Drivers Association said: 'This affair, and the cover up, is nothing short of a national scandal and the LTDA is therefore calling for a parliamentary enquiry to establish what went on and who was responsible.'

The emails No10 said didn't exist

Just over a year ago, Downing Street was served with a formal request under the Freedom of Information Act.

It came from Christopher Morris, a political aide working for the Liberal Democrats in the London Assembly, and it sought to get to the bottom of a sensational rumour sweeping City Hall.

Mr Morris had been reliably informed that David Cameron and George Osborne had overseen a vigorous secret lobbying campaign to stop Boris Johnson from seeking to tighten regulations on the taxi firm Uber.

According to his sources, the pair had tasked Daniel Korski, deputy head of the prime minister’s policy unit, with ensuring that London’s mayor did nothing whatsoever to upset the Californian web company.

Back in September 2015, Mr Johnson had announced a ‘Private Hire Regulations Review’ in which he floated a number of potential policies designed to rein in Uber, which runs a mobile phone app that allows users to hail a minicab at the push of a button.

He wanted, among other things, to ease congestion, increase passenger safety, and protect the livelihoods of traditional black cabbies, who were being driven out of business by the low cost rival. But in January 2016, the mayor announced that almost all of the proposals were to be dropped.

The big question is: why? Mr Johnson insisted the climbdown followed a public consultation.

But Mr Morris had been told that the move came after the mayor was summoned to meetings at which Mr Korski and senior ministers, including Business Secretary Sajid Javid, had personally ordered him to lay off Uber.

He believed that Mr Korski had also bombarded officials at Transport for London, which was in charge of the review, with calls and emails and met with them to water down any regulations.

Some of the phone calls and other messages circulated during this campaign had, he was told, been very hostile indeed.

That was the rumour, at least. To see whether it might be true, Mr Morris asked Downing Street in late February to send him details of ‘all correspondence since January 1st 2015’ between Mr Korski and either the mayor’s office, or TfL.

On March 30 last year, Downing Street responded, in a letter sent on headed notepaper and signed by Nicolas Howard, assistant private secretary to Mr Cameron.

It was short, unequivocal, and to the point: ‘We do not hold information in relation to your request.’

In other words, the prime minister’s office was saying it had no record, whatsoever, of any correspondence between Mr Korski and officials who worked for either TfL or for Mr Johnson. No emails, copies of letters, or notes of phone calls existed.

The letter was sent under the terms of the Freedom of Information Act 2000, which requires government officials – who are, of course, servants of the public – to answer all requests truthfully.

However as the Mail revealed on Saturday, several emails were in fact sent from Mr Korski’s government email account to senior figures working for both Johnson and TfL during the period in question.

They emerged courtesy of a second freedom of information request, this time submitted to Transport for London by Mr Morris, asking for any correspondence involving Mr Korski and its officials.

In response to the request, TfL had produced a dossier of emails, including three that the Downing Street aide wrote in October 2015, and four that were sent to him around the same time.

Two were sent by Mr Korski to Leon Daniels, the managing director of surface transport at TFL, and carried the subject: ‘Regs review – follow up.’ They revealed that the Downing Street aide had met and corresponded extensively with Mr Daniels to ensure that Mr Johnson’s review was headed in what he called ‘a sensible direction’.

Mr Korski’s other email was sent to Isabel Dedring, Mr Johnson’s deputy mayor in charge of transport as part of the same email chain, setting up a meeting to discuss ‘options’ to resolve the disagreement between No 10 and the mayor’s office.

The cache of emails also revealed that Mr Korski had sat in on a meeting held on December 16, 2015 at which Mr Johnson discussed Uber with Sajid Javid, and Cameron ally Oliver Letwin.

An official note recorded that ‘different views were exchanged’.

Since these messages would all have been sitting on Downing Street’s email servers, at the time Mr Howard wrote his March 30 letter to Mr Morris, it’s hard to understand how they were not found and disclosed.

After all, a search Mr Korski’s email account would have instantly turned them up, at the push of a button.

Downing Street last night formally denied any cover up in relation to the FoI inquiry, and we must of course at this stage take them at their word.

Yet what cannot be denied is that both Mr Cameron and Mr Osborne, not to mention Mr Korski, had plenty of reasons for wanting their advocacy work on behalf of Uber to remain firmly out of the public domain.

The American internet company pays almost no tax in the UK, funnelling its British revenues to the tax haven of Bermuda, via the Netherlands. As such it makes a peculiar organisation for Downing Street officials, not to mention a British chancellor and prime minister, to be lobbying for.

Since London transport is fully devolved to the mayor, it’s also a policy area that they are supposed to have no responsibility for.

Yet – crucially, perhaps – the firm also happens to have since early 2015 employed one of Mr Cameron and Mr Osborne’s closest personal friends, 49-year-old Rachel Whetstone, as one of its most senior UK executives.

The godmother of Cameron’s late son Ivan, and a chum of both men’s respective wives, she and her husband Steve Hilton (the ex PM’s former director of strategy) even bought a holiday cottage near the Camerons’ country seat in the Cotswolds.

In other words, the then prime minister’s lobbying on behalf of Uber could have given an appearance of serious impropriety – leading to allegations that he was granting special favours for a friend.

For Mr Osborne, the picture looks doubly awkward, since one of Uber’s major investors, US finance house BlackRock, recently employed him on a salary of £650,000 to work 48 days a year as an adviser.

Quite how the duo intend to justify their secret lobbying for the Californian technology firm remains a mystery: neither has yet commented on it. Exactly why Downing Street failed to disclose its record of this lobbying campaign, in apparent contravention of the Freedom of Information Act, is also unclear – though it should be noted that Mr Howard was made a Companion of the Order of the Bath in Mr Cameron’s resignation honours.

What few will argue with, however, is that only a rigorous parliamentary inquiry can now hope to get to the bottom of what really went on, in this increasingly murky affair.

Was a deal done at Sexy Fish restaurant?

With its gold leaf ceiling and glittering contemporary sculptures, including a naked blue mermaid by Damien Hirst, Mayfair’s Sexy Fish restaurant was quite the scene when it opened just before Christmas 2015.

Kate Moss and Cheryl Cole were spotted tucking into its pan-Asian menu, which sold steak at £110 a pop and a plate of sashimi for £65 beyond its crystal-encrusted front door.

Yet on December 22 that year a very different crowd headed into its basement private dining area, with its pink marble floors and what purports to be the world’s largest coral fish tank. David and Samantha Cameron sauntered into the venue, closely followed by Chancellor George Osborne and his wife Frances.

They were there at the behest of a woman who was once, rightly, described as one half of the ‘power couple behind the Tory throne’.

Mayfair’s Sexy Fish restaurant was quite the scene when it opened just before Christmas 2015

She was Rachel Whetstone, wife of Mr Cameron’s former policy guru Steve Hilton, godmother to his late son Ivan, and one of his oldest personal friends.

The occasion was a Christmas party, organised at great expense so that a few dozen of the extraordinarily well-connected PR woman’s closest chums and contacts could toast the festive season.

Also on the guest list were a smattering of mostly Left-leaning journalists, including Newsnight boss Ian Katz and his wife Justine Roberts, who runs the internet site Mumsnet; Sunday Times scribe Camilla Cavendish, who had just been made head of the No 10 policy unit and was this year handed a peerage; and journalist Jenni Russell, whose child can boast Ed Miliband as godfather.

At the time, the bash made some unflattering headlines. As Quentin Letts perceptively wrote in these pages, the event only added to the impression that in the era of Cameron, Britain was being run by a moneyed chumocracy ‘detached from the masses’.

Today, that glitzy soiree is starting to look even more ill-advised.

For as the Daily Mail revealed on Saturday, it occurred at a time when Mr Cameron and Mr Osborne were secretly devoting an extraordinary amount of their energy to a lobbying campaign designed to benefit Miss Whetstone’s company, Uber.

Intriguingly, one of the lucky few who Miss Whetstone ensured could rub shoulders with the two most powerful men in Britain at the bash was Tim Allan, a lobbyist who runs Portland Communications.

He once, several years earlier, gave her a job. By happy coincidence, when she moved on to Google and then Uber, those companies gave lucrative contracts to Portland.

All of which meant that, for several hours in London’s most fashionable restaurant, the Prime Minister and Chancellor found themselves alongside Uber’s head of communications (Miss Whetstone) and the man in charge of its lobbying firm.