When Boris Johnson's 'New Routemaster' buses are introduced on a cross-river route for the first time they will be without one of their main selling points - the open platform.
The Mayor of London has made much of the reintroduction of the open platform on the new buses, which allows passengers to get on and off the bus between stops.
"Passengers rate the new vehicle very highly and relish the return of hop-on hop-off travel," Boris Johnson said last year.
Now Transport for London has confirmed that there will be no conductor on board when the buses are brought into service on route 148 this Saturday.
All three doors will be controlled by the driver and will be opened at stops.
The 24-hour route 148, which is operated by London United, runs between Camberwell Green and White City via Elephant & Castle and Westminster Bridge.
During peak hours, 25 of the new buses will be in passenger service to carry the 22,000 people who travel on the route each weekday.
The five routes currently served by 'New Routemasters' all remain north of the Thames.
All the buses on those routes have a second crew member on board during weekday daytimes, apart from the small number of prototype buses used alongside conventional vehicles on route 38.
"The New Routemaster buses are becoming an increasingly familiar sight on the capital's roads with the conversion of more routes continuing apace," said Leon Daniels, Transport for London's managing director of surface transport.
"With the introduction of the very latest Euro VI engines, the environmental credentials of the greenest diesel electric hybrid bus in the world are set to get even better."
Several 'New Routemasters' were pressed into service on route 148 last week to provide extra capacity during the tube strike.
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