British Rail Class 332

The Class 332 was a fleet of fourteen four- and five-car 25 kV AC electric multiple unit sets built in 1997–98 by CAF (Construcciones y Auxiliar de Ferrocarriles) of Beasain, Spain, with electrical equipment by Siemens, designed exclusively for the Heathrow Express premium airport rail service between London Paddington and Heathrow Airport. The Heathrow Express was a joint venture between BAA (British Airports Authority) and Railtrack, opened in 1998 to provide a high-frequency, non-stop, fifteen-minute journey between Paddington and Heathrow's central terminal area — a service premium in both speed and comfort over the Underground's Piccadilly Line.

The Class 332 was designed to the highest specification of any British EMU of its era, befitting its role as a premium product competing for the business travel market. The interior was configured with an airline aesthetic: two classes of accommodation (First and Express, the latter being standard class), with individual overhead luggage racks, moulded airline-style seats, at-seat power points, and a clean, modern cabin environment that bore no resemblance to the utilitarian interiors of contemporary commuter EMUs. The fifteen-minute journey time demanded high acceleration and deceleration, and the Class 332 was designed accordingly, with a maximum speed of 100 mph and a braking performance calibrated for the short, fast Heathrow Express schedule.

Fourteen sets were built: ten four-car sets (332001–332010) for the standard service and four five-car sets (332011–332014) for additional capacity. They entered service in June 1998 with the opening of the Heathrow Express and worked the service without major interruption for over twenty years, providing a consistent and highly-rated airport rail experience. The sets were maintained to an exceptionally high standard throughout their service lives, with regular interior refreshes that kept the passenger environment competitive.

The Class 332s were withdrawn in 2020 as Heathrow Express made the decision to use Class 387 Electrostar sets from the Great Western Railway fleet for the Heathrow Express service — a fleet-sharing arrangement that eliminated the dedicated Class 332 fleet and reduced operating costs. The withdrawal ended twenty-two years of service and brought to a close the most luxurious dedicated airport rail fleet Britain had produced. At the time of writing, the disposition of the Class 332 fleet remains uncertain, with discussions about potential export or alternative use ongoing.