Features

By BBC London's political editor, Tim Donovan

They've sought them here, they've sought them there.

For weeks a crack squad of Labour gaffe-hunters has had Boris Johnson under surveillance - hoping for the merest whiff of a miscalculation, the tiniest evidence of mouth detatched from brain.

Another attack on Saint Jamie Oliver perhaps? Or - with Liverpool now firmly despatched - a full-frontal assault on another major city? Even better, obviously, if it's a particular community in London.

The Gaffe Squad

Now at last those gaffe-hunters - grown increasingly desperate - believe they've got their reward. And not just one but - in the finest traditions of London transport - two blunders coming along at the same time.

Two iconic symbols of London

In his transport manifesto, Boris Johnson pledges he'll phase out bendy buses and replace them with a new (yet-to-be-designed) fleet of Routemasters.

And he claims the cost of bringing back inspectors for this fleet will be eight million pounds.

Ken Livingstone's team claims this under-estimates the actual cost by a cool £100 million.

How they come to this nicely evocative round figure is the cause of much dispute, but it's based on a number of factors they claim Johnson has failed to consider.

The counter-claims

Firstly, they say Johnson made a fundamental error, basing his claim on the cost of one conductor per bus whereas in fact, because of the shift system, it should be three. That's £25 million, not eight million.

Then they claim that any given new Routemaster is likely to be smaller than a bendy bus, so there will need to be more of them to maintain capacity: at least 200 more.

They will need not only three conductors each, but new drivers too. Another £35 million.

Finally, they say that the costs of manufacturing and introducing a new model of this sort - what they called 'replacement' costs - will be another £25 million.

Lies, damn lies... And statistics

As you will see, this total falls short of the current mayor's magic £100m claim. That's because, his aides say, the above figures are all under-estimates.

The two rivals at a hustings

It won't be the last time that statistics get a good pummelling during this election.

According to the Guardian, one firm of independent transport consultants have said the Conservative plans 'don't add up' and the cost is 'nearer' Labour's estimates.

They don't though say how near.

Standing his ground

Facing calls to go back to his calculator, Boris Johnson is holding his ground, insisting that there's bound to be a fluidity to the figures, given he can't know yet how soon the new buses can be rolled out but that their introduction will - of course - be phased.

But he's also come under fire for a promise - revealed before the Home affairs committee - to recruit and dedicate 440 extra police community support officers - to patrol the buses and make passengers feel safer.

This, he claimed, would be paid for from £16 million pounds cuts he would make to the press and publicity budget of Transport for London.

Labour say that he used old TfL budget figures - still to be revised - and that TfL have already promised the PR savings for next year.

Accusing them of 'shifting the goalposts' Boris Johnson says it remains his intention to go ahead anyway, taking the money from the same TfL department.

What with smaller busers, filled with all these inspectors and uniformed officers, one wonders how much room will be left for passengers?