These are the last survivors of a fleet of 10 vehicles converted from 1959-built 2-HAP units in 1983 – 4. They are powered by two EE507 dc motors, providing 185 kW each to assist the Class 73 locomotives they normally run with. This combination operated the Gatwick Express service for 20 years before being replaced by the Class 460 units, although one set remains in use as maintenance cover for the new trains. Construction is all steel “Mk 1” design with Mk 4 bogies, which require frequent maintenance to retain their 90 mph speed certification. Apart from the cab the vehicles are simply an empty van area with side protection making it suitable to carry airport luggage trolleys. Multiple control is suitable for all 1960s – style southern region vehicles.