The Enviro400 City can trace its design roots back to 1997, with the introduction of the Dennis Trident 2, one of the first low-floor double-decker buses to enter service.

The model saw immense success at the turn of the millennium, despite financial difficulties facing Dennis Specialist Vehicles during this period.

[18][19] Nineteen Scania N250UDs with Enviro400 City bodies were delivered to First Eastern Counties for their flagship 'Excel' services in 2020, featuring high-specification interiors, next stop announcements and camera mirrors.

[20] The Enviro400 City was initially launched on the Enviro400H hybrid electric platform developed by Alexander Dennis and BAE Systems, which was carried over from the previous Enviro400.

[26][27] The Enviro400 City CBG was launched in 2016 at the Euro Bus Expo, built on the Scania N280UD compressed natural gas-powered chassis.

Due to First's Bristol depots being unable to support the route at the time, the buses were originally subcontracted out to CT Plus Bristol,[36] although eventually Lawrence Hill Depot was upgraded to service such buses, and in September 2022 the original fleet passed to First, following financial difficulties faced by CT Plus.