The British Rail Class 322 were electric multiple unit passenger trains which were built by British Rail Engineering Limited in 1990 for the Stansted Express service from London Liverpool Street to Stansted Airport. After becoming surplus to requirements on this route, the fleet saw further use with a number of other operators. Description In 1987 British Rail (BR) was extending electrification north from London Liverpool Street towards Cambridge. Included in this plan was the construction of new branch line, diverging from the main line at Stansted Mountfitchet, to serve the newly built Stansted Airport station, which opened in 1991. BR decided to build a dedicated fleet of units to work a new service, the Stansted Express. The Class 322 units were built to the same basic design as the Class 321 units, which were still under construction for services on the Great Eastern Main Line and West Coast Main Line, but with a larger First Class area in the DTCO resulting in a different window arrangement. Although the Stansted route fell under the jurisdiction of Network SouthEast (NSE), the units were delivered into service in a special white livery with a broad green band, instead of the more usual NSE blue/red/white livery. Five 4-car units were built, numbered 322481–322485. Each unit consisted of two outer driving trailers, an intermediate trailer, and an intermediate motor coach, arranged and numbered as follows: Originally the units had a lower density 2+2 seating arrangement in Standard Class appropriate to their use on airport traffic, but during their C6X refurbishment between 2005 and 2007 the units were converted to standard-class only and fitted with high-density 3+2 seating. The DTC and DTS vehicles were redesignated DTS(A) and DTS(B) respectively at this time. Following transfer from First ScotRail to Northern Rail in 2011, the first-class seating was refitted to the DTS(A) vehicles; but it was removed again in 2015 and replaced with a universally-accessible toilet. At this point the DTS(A) and DTS(B) vehicles were respectively redesignated DTSL and DTS. Operations Network SouthEast On introduction in 1990 the Class 322s were painted in a joint livery for Network SouthEast (NSE) and British Airports Authority consisting of a light grey and white body with green waist band lettered "Stansted Express" on one side and "Network SouthEast" on the other. Until opening of the Stansted Airport spur the units worked peak-hour services between Cambridge and Liverpool Street, but also found