Bombardier has delivered its first Class 710 EMU to client London Overground.
The new Overground fleet is due to enter service on the newly electrified Gospel Oak to Barking line by November.
TfL confirmed that final approvals for the route were completed last week.
Bombardier is building 54 new trains for London Overground. The four-car units, which feature a new colour scheme, will double the capacity of the existing diesel stock and production has supported a number of jobs at Bombardier’s factory in Derby.
The first eight trains will enter service on the Gospel Oak-Barking line before being rolled out to the Watford-Euston route and to run services from Liverpool Street to Cheshunt, Chingford and Enfield Town.
Class 710s will also be used on the Barking Riverside extension when it opens in 2021.
Driving training is due to take place over the summer.
New features include intelligent lighting, USB charging points and Wi-Fi.
TfL said that 50 per cent of the suppliers used to build the new fleet are based in the UK.
Jonathan Fox, TfL’s director of rail and sponsored services, said: “Our new state-of-the-art British built London Overground trains will be an exciting addition to London’s transport network and help boost capacity on some of the most busy and popular lines.
“We are very keen to see them introduced into service as soon as possible so our patient customers can benefit from the fully air-conditioned, walk-through trains with handy USB charging points and real-time passenger information screens.
“Over the summer, the new trains will undergo final rigorous testing and drivers will complete extensive training. We are now planning for the first trains to enter passenger service on the Gospel Oak to Barking route by November.”