London's mayor said today that he wanted a new double-decker bus with the familiar open platform design to be on the streets before the 2012 Olympics.

Transport for London has selected Wrightbus, a family-owned company based in Northern Ireland, to build the buses.

"The countdown is now well and truly on as Wrightbus work nineteen to the dozen to deliver Londoners their new bus in 2011, ahead of the world descending on the city for the 2012 Games," mayor Boris Johnson said in a statement.

Johnson has led a campaign to develop a new version of the classic Routemaster red buses after they were largely phased out in 2005 after half a century of service.

The restoration of the open platform will allow passengers to hop on and off the bus if it is slowed in heavy traffic. It will be possible to close the platform if required, for instance at night.

The bus will have the capacity to carry at least 87 passengers and will incorporate hybrid engine technology to improve fuel consumption and cut emissions.

Snub-nosed and light-bodied, with the driver enclosed in his cab and a conductor taking the fares, the Routemasters were built until 1968. At their peak, 2,760 trundled throughout London but now only a handful are left on so-called "heritage" routes.

The open-door rear, which allowed passengers to get on and off whenever they wanted was one of their strongest features -- albeit one which health and safety officials frowned upon.