Now travel group wants to save the bendy bus

London TravelWatch said there are many advantages in keeping them and they have proved popular on busy routes.

It puts the capital's watchdog in direct conflict with Mayor Boris Johnson who made a manifesto pledge to scrap the bendy bus.

Janet Cooke, chief executive of London TravelWatch, said scrapping the buses on some of the capital's busiest routes and replacing them with conventional vehicles could cost an extra £13 million a year.

Ms Cooke wants Transport for London to conduct extra research among passengers on the routes before taking them off the streets.

Bendy buses have had a troubled history since being introduced by Ken Livingstone. Some earlier models caught fire and they have been condemned as "intimidating" and "inappropriate" for London.

They have also been beset with fare-dodging passengers using the rear section, away from the driver, to get on an off.

Ms Cooke said: "We believe the use of articulated buses on routes with a high volume of passengers has overwhelming advantages."

She said they were more accessible, could manoeuvre in tight spaces and passengers could get on and off quicker.

"They are particularly suitable for use on routes which serve mainline railway termini, where numerous passengers arrive at stops in short spaces of time. We see no reason to scrap these buses."

The watchdog said the bendy buses performed well and are popular on a number of routes. It highlighted route 521 (between Waterloo and London Bridge via Holborn;) 507 (Waterloo and Victoria via Westminster) and 38 ( Victoria and Clapton Pond via the West End and Islington).

Ms Cooke said; "The cost of using conventional buses on these routes may by significantly higher than using bendy buses.

"We have estimated, and TfL has not disputed the figure, that additional costs on these three routes alone could be in the region of £12-13 million per annum."

TravelWatch also raised concerns about the potential impact of the extra buses needed to replace the bendy models on congested streets and at stops.

"The 38, for example, serves an area of Islington and Hackney not served by the Tube and when double deckers were used previously passengers often couldn't board the first bus, a situation we believe rarely occurs now," continued Ms Cooke.

"Feedback we have received suggests that many people favour the retention of bendy buses on these routes.

"We would like TfL to undertake - and publish - some research into the preferences of people who actually use these routes before any changes take place."

The Mayor, in his manifesto, said bendy buses "were never suited to London's roads and the facts show they have twice as many accidents as normal buses".

He added: "In addition, open boarding means they have become known as 'free buses'. They lose almost three times as much fare revenue as other buses."