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.

Why then, he asks, did the the small Northern Irish company Wrights - which had previously built buses on existing Volvo chassis - get the contract to create the all-new bus and why did the Heatherwick studio get the gig to do the interior and exterior?

Ponsford and Alexander Dennis are, to put it mildly, cheesed off. Worse still for ADL Peter Hendy, boss of Transport for London told me last year that he wanted all future buses purchased for the network to use the NB4L formula of three doors, two staircases and a range-extender electric drivetrain.

Alexander Dennis officials asked Hendy whether this meant their company was now excluded from one of the world’s biggest bus fleets. Hendy told me what he told Alexander Dennis – the company could supply buses, but they had to mirror the NB4L format. In a reflection of how the bus world has been shaken up by the application of car industry-style concepts and scoop shots, Ponsford’s PDF essay ends with a couple of sneak-peak renderings of the Alexander Dennis three-door London bus.