Yesterday, the curiously nameless ‘New Bus for London’ carried fare-paying passengers for the first time. It ran as a No38 from Hackney in the north east of the city to Victoria bus station near Buckingham Palace.

I couldn’t get on it: it was packed with enthusiasts, keen for a piece of public transport history. However, with less than 80 days to go to the London Mayoral elections, the bus’s arrival has sparked a political mud fight.

For Mayor Boris Johnson’s team, the NB4L represents a breakthrough in environmentally friendly public transport, designed, engineered and built in the UK. Boris promised the new bus would be on the roads in his first term: amazingly, he met his pledge. For the opposing candidate, and former Mayor, Ken Livingstone, the bus is a ‘vanity project’ which sees each bus cost ‘over £1m’.

And weighing in from the bus world is Alan Ponsford, boss of Capoco, one of the world’s leading bus designers. Ponsford, keen Autocar readers might remember, was responsible for the original ‘New Routemaster’ design that I commissioned for the Christmas 2007 edition of the magazine.

But Ponsford isn’t happy. Earlier this month he wrote an amusing and erudite article, considering the way that, what began as a ‘bit of fun for… Autocar’, rapidly turned into a real-world project. ‘The firestorm of popular and political reaction took us by surprise’ he says.

The rather lovely cutaway Ponsford’s team created for us – showing how an electric range-extender drivetrain could be used to create a new bus with a open rear deck – was the key to unleashing Boris Johnson’s dream of a new Routemaster.

As a UK bus industry grandee later commented, when studying this cutaway view, “That image is what made it real; made it possible.”

'So yes, maybe that image is worth the 20,300 words of [think tank] Policy Exchange’s “Replacing the Routemaster” call to arms’ Ponsford writes.

Ponsford further worked up the Autocar proposal, which came joint-first with the Foster-Aston Martin entry in Boris’s formal bus design competition. Ponsford reveals that long-established bus maker Alexander Dennis (ADL) were involved in the both the winning Capoco and Foster-Aston proposals.