The Alexander ALX400 (later known as the TransBus ALX400/Alexander Dennis ALX400) is a bus body built by Alexander Dennis; it is part of a new generation of mainly low-floor bus chassis first produced in the late 1990s by Walter Alexander Coachbuilders. It was one of the ALX-series, all except ALX100 feature the same designs on the front and rear panels.Released in 1997, the ALX400 is the 2-axle double-deck variant of series. It replaced the aging R-series bodies and was fitted to numerous chassis, including the Dennis/TransBus Trident, the DAF/VDL DB250LF and the Volvo B7TL. It proved a big success with national operators; huge numbers serve London and the rest of the United Kingdom.