These locomotives are unique in the UK in that they can operate from the 750v dc 3rd rail or independently using their own diesel power unit. Originally built by English Electric in 1967, the locomotives were used on the Gatwick Express airport service as support to the Class 460 trains until July 2005. Many have now been sold to operate infrastructure trains and some to preservation. They can operate in multiple with southern “slam door” stock, or with Mk 2 Gatwick express sets including a Class 489 GLV. Operating on diesel traction their capacity is more limited, but still adequate for infrastructure trains and trip freight workings. The locomotives have long had a reputation for reliability, which has been maintained to this late stage in their lives.