On Saturday the route 24, which runs between Hampstead Heath and Pimlico, will become the first in the Capital to operate entirely with New Bus for London vehicles.
During peak hours, 27 of these cutting-edge new buses will be in passenger service to carry the 28,000 people who travel on the route each day.
The route, operated by Metroline, runs from Hampstead Heath to Pimlico via Victoria, Westminster, Trafalgar Square, Leicester Square, Warren Street, Mornington Crescent and Camden.
Mayor of London Boris Johnson said: 'All the way from Hampstead Heath to Pimlico, Londoners can now hop aboard the world's cleanest, greenest bus of its type.
'I hope people feel pride as they ride on this brilliant feat of British engineering, content in the knowledge that they are supporting jobs up and down the country.'
The New Bus for London is the greenest diesel-electric hybrid bus in the world.
In recent emissions tests a prototype bus, that had been in passenger service for eight months and that had driven more than 15,000 miles, was found to emit a quarter of the NOx and PM of a fleet average hybrid bus and 20 per cent less carbon dioxide.
When all 600 New Bus for London vehicles are in service in 2016 it will reduce CO2 emissions in the Capital by around 20,600 tonnes a year.
The buses are manufactured by the family-owned Wrightbus company in Northern Ireland.
The order for the 600 New Bus for London vehicles has resulted in the opening of a new chassis plant in Antrim and the safeguarding of 220 jobs, including 18 apprenticeships and the creation of 50 new jobs.
As well as the manufacture of the chassis and superstructure in Northern Ireland, a number of components for the new bus are made by companies from around the UK; including engines from Darlington, seats from Telford, seat moquette from Huddersfield, wheelchair ramps from Hoddesdon (Hertfordshire), destination blinds from Middleton near Manchester, tyres from Ballymena and flooring from Liskeard (Cornwall).
All of these companies have received a boost as a result of the new bus project.
Investment in London's transport network is safeguarding jobs across the whole of the UK, with more than 60 per cent of TfL's spend through its supply chain going to suppliers outside of London.
Investment in London's transport network supports 40,000 jobs in the UK supply chain, with a further 19,000 supported in the supply chain within London.
The construction of Crossrail is also bringing huge benefits to UK PLC.
Throughout the project and its supply chain it is estimated that enough work will be generated to create the equivalent of 55,000 full time jobs.
The route 24 which is operated by Metroline, will be followed by the route 11 which will be converted to New Buses on 21 September.
The route 11 is operated by Go Ahead and runs from Liverpool Street Station to Fulham Broadway via Bank, Mansion House, St Paul's, Ludgate Circus, Fleet Street, Aldwych, Trafalgar Square, Westminster, Victoria, Sloane Square and Chelsea.
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