Trains are occasionally late, but these trains should have arrived more than a year ago.
The brand new four carriage electric trains were expected to be running on the north London Gospel Oak to Barking line in January 2018. But they were not ready in time, and the existing stock had already been sold on.
Transport for London borrowed three trains from other Overground routes to keep the line running, but rail users saw services dwindle from four an hour to just two.
The delay was caused by software problems with the new trains.
But now the new walk-through trains have finally arrived, and they come with air conditioning, USB points and real time infomation screens. Each will carry nearly 700 people, nearly twice as many as the old trains.
The launch of two new trains is the first step towards a full service being back in place between Gospel Oak and Barking. Once they all arrive over the summer a full timetable will run again, TfL say this should be by September.
When all the new trains are in place on the Gospel Oak to Barking line TfL will start introducing them onto the Watford Junction to Euston route, and finally to the Liverpool Street to Chingford line. A TfL spokesperson said it was hoped this would be by the end of this year.
Users of the Gospel Oak to Barking line will be offered one month's free travel in September, funded by Bombardier, the train manufacturer.