A new version of the iconic Routemaster bus could be back on the streets of London by 2011, according to Transport for London.

The announcement came as London mayor Boris Johnson crowned designs by Aston Martin and architect firm Foster and Partners the winners in a competition to design the successor to the driver-and-conductor Routemaster.

The other joint winner for the new-look, stylish, "greener" double-decker was bus, coach and truck design company Capoco Design. The winning designs will now be passed on to bus manufacturers to develop into a final proposed design.

Overall, 700 entries were received from professionals and non-professionals of all ages, from London and across the world.

TfL said it expects to award a contract to develop and build the first new bus for London towards the end of next year.

Transport commissioner Peter Hendy said: “We now have a wealth of fantastic ideas to present to the bus manufacturers who will create the final design of the new bus for London, due to hit the streets in 2011.”

Boris Johnson said: “We have had a phenomenal response, with ideas submitted from around the globe, and we now have, in our joint winners, two stunning designs that allow us to go forward and produce a truly iconic bus fit for 21st Century London.”

Labour's transport spokesperson on the London Assembly, Val Shawcross, said the competition was not a serious way to make transport policy and called it a waste of public money.

"I have yet to hear one convincing argument for why London needs a new double-decker bus and until Boris comes up with some, Londoners will see this as little more than a vanity project," she said.

The original Routemasters were phased out from regular service by the end of 2005 as they were inaccessible to wheelchairs or pushchairs.