In the first thirteen years of this century something remarkable happened in London.

Despite a huge increase in the number of people living in the capital, the number of people driving cars fell dramatically.

In every other part of the UK, car use increased but in London people started using buses, trains and bicycles to get to work instead.

In 28 out of 32 London boroughs, motor vehicle traffic fell significantly over the past 13 years, with the biggest falls in central London.

This shift was not an accident. It was a deliberate result of public policy.

Under Ken Livingstone billions were spent on public transport in an attempt to get people out of their cars. Livingstone's combination of congestion charging and new transport connections was hugely successful. It was a remarkable achievement over a period when the number of people living in the capital boomed.

The long consensus, pushed by road lobbyists and the government alike, that car use would continue to rise inexorably had been broken.

This was a huge victory for those who wanted to make London a more liveable city. It was also a major threat to those whose financial interest lay in maintaining the status quo of putting more and more cars on the road.

For some time it looked like the battle was being won. Sadly the current Conservative mayor of London, Boris Johnson, has decided to abandon this agenda.

His decision to scrap the western extension of the congestion charge and the millions it provided for investment in public transport was just the first step in a new rabidly 'pro-car' agenda for London.

His next step is to build a series of new roads across the Thames in East London. First up is the Silvertown Tunnel on the Greenwich Peninsula. This PFI-funded tunnel would cost close to a billion pounds and appears to have the sole purpose of making it slightly easier for people to drive from Kent to Canary Wharf.

However, even this aim is likely to be frustrated. The last time a tunnel was built on the Greenwich Peninsula, traffic using the crossing at peak times doubled within a year. With southern approach roads already inadequate, the tunnel is likely to cause even longer journeys for Kent bankers heading home after work.

Meanwhile, the people who actually have to live by the road will continue to suffer some of the worst air quality in the country. Recent studies found that pollution in the area is already well above safe and legal limits. With around 4,000 people already dying every year as a result of pollution across London, Johnson's plans will only make this worse.

Not willing to stop there, the mayor plans another new East London bridge between Beckton and Thamesmead, effectively resurrecting proposals inherited from Livingstone. Thamesmead, which is one of the poorest and most deprived parts of London, remains one of the only parts of the capital without a single train, Tube, tram, or DLR station. Proposals to extend the London Overground across the river have long been mooted but never taken up. Instead residents can expect to have a four-lane motorway dumped on them instead.

Further plans for another East London bridge at Belevedere are also in discussion with Bexley council, alongside separate government plans for a second river crossing at Dartford, also backed by Johnson.

Unfortunately Johnson's fervour for more roads doesn't stop there. Under proposals released earlier this year, two new underground motorways costing £30 billion would be built in central London with exit portals belching fumes onto London's streets at various points around the centre.

This last plan is so ludicrous it's hard to imagine it ever happening, but the fact that Boris is even suggesting it shows just how far we have come from the radical agenda first pursued by Livingstone.

All of Johnson's new roads are being planned on the assumption that London's population and therefore its number of drivers is set to rise. However, this goes against all the evidence of the past 13 years, where car use has plummeted at the same time as the population has boomed.

Rather than being inevitable, rising car use only occurs as a result of deliberate public policy - a deliberate public policy that Johnson has now decided to adopt.

The plans also go against the grain of Johnson's other multimillion pound proposals to increase cycling in London. It takes a special level of incompetence to spend millions encouraging people out of their cars in one part of London, only to spend billions more encouraging them back into their cars in another part of London. It's like a homeowner buying a rat-killing cat, only to then decide that what the place really needs is a few hundred more rats.

Yet those looking for a change of heart from the next mayor are likely to be disappointed. All of Johnson's road-building plans have received either tacit or explicit support from members of the Labour party. With politicians of both major parties apparently terrified of offending motorists, it appears there is no road-building plan too expensive, dirty or counter-productive for Labour to back.

Yet what this consensus ignores is that building new roads actually hurts motorists. All the evidence from previous road-building programmes shows that when you build more roads, you get more cars, with congestion quickly returning to levels seen before you spent billions trying to solve the problem.

This is especially the case in big cities where demand for road-space is always going to be greater than the supply. This is exactly why the congestion charge was necessary and further road-charging is inevitable in London, whether Boris spends billions on building new roads or not.

Other countries have long realised all of this and spent decades ensuring their cities are designed for cyclists, pedestrians and public transport users rather than cars.

In the first ten years of this century, London finally seemed to have woken up to this reality and its leaders seemed to be taking the right steps to make it happen.

Sadly for Londoners, Johnson and his likely Labour successors are intent on bringing us all right back to square one.