The Class 332 EMUs are used exclusively on the Heathrow Express out of London Paddington. The trains leave for the airport every fifteen minutes on a non-stop journey which takes fifteen minutes. Similar units known as the 
Class 333 operate in the North of England.
| Information | 
| Number built: | 61 (14 4 and 5 car sets) | 
| Built: | 1997-98, 2002 | 
| Builder: | CAF Siemens | 
| Engine: | 4 Siemens traction motors (25kV AC OHLE) | 
| Power: | 1, 877 hp (1, 400 kW) | 
| Formation: | Driving Motor First Open (DMFO)+Trailer Standard Open (TSO) +Pantograph Trailer Standard Open Kavatory (PTSOL)+
 Driving Motor Standard Open (DMSO) or
 DMSO+TSO+PTSOL+Driving Motor First Lavatory Open (DMFLO)
 (5 car sets have an extra TSO)
 | 
The EMUs were originally delivered as three-car sets but have been reformed as four and five car sets with further car deliveries. There are nine four-car sets and five five-car sets [1]. They were the first electric trains to operate on the Great Western Main Line after a portion was electrified as far as the airport junction.
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| 332 012 passes through Ealing Broadway heading for Paddington | 
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| 332 001 up on jacks at the Heathrow Express depot at Old Oak Common | 
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| Interior of 332 003 | 
|  | 
| Another view inside Old Oak Common depot | 
|  | 
| Cab of 332 003 | 
|  | 
| 332 006 waits to depart at London Paddington | 
[1] Colin J. Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 266