[12][13] In the 1990s, London Underground designed an open gangway "Space Train" with walk through carriages to increase capacity in the deep level tube.

[21] Metronet, the private consortium responsible for the infrastructure on the Victoria line, collapsed in July 2007 due to financial difficulties.

[23][24] The second pre-production train was expected to begin trial running in full passenger service in July 2008.

[28][29] During the morning rush hour on 21 July 2010, a train broke down at Pimlico, and ambulances had to be called in to rescue almost 3,000 trapped passengers.

Five days later, on 26 July 2010, another morning rush-hour train broke down at Oxford Circus, causing all Victoria line services to be temporarily suspended.

Transport for London cited software failures and over-sensitive door sensors as the main causes of both problems.

[30][31] Subsequent analysis has used the analogy of the bathtub curve to explain the large number of early issues with the trains.

[36][37] Built as part of the Victoria line upgrade in conjunction with new signalling, the trains were designed to decrease journey times, improve reliability to minimise long term maintenance costs, as well as increase passenger capacity per train.

[4] The trains were built using Bombardier's FICAS technology, giving a thinner bodyshell and more internal space for passengers.

The electrically powered train doors are wider for easier and faster boarding and alighting of passengers in order to reduce dwell times in stations.

[43] They are the first London Underground trains to be designed since the Rail Vehicle Accessibility Regulations were introduced,[46] so they have more facilities for people with impaired mobility, including multi-purpose areas with tip-up seats and space for wheelchairs and pushchairs, and offset centre door poles for wheelchair access.

[53][failed verification] The trains are maintained at the Victoria line's Northumberland Park Depot, with Bombardier staff on site for warranty parts replacement.