- Driving Motor Brake Second, originally part of a 2-car set (DMBS + DTCL)
- Twin AEC 6-cylinder diesel engines, 150bhp each
- Mechanical transmission via 4-speed epicyclic gearbox
- Maximum speed of 70mph
Built by Park Royal Vehicles in 1957–58 as one of just 20 sets constructed to this design — a private build for British Railways using standard mechanical equipment underneath a Park Royal body. 50413 entered service in October 1958 allocated to Ryecroft, working the routes radiating from Walsall, before moves through Monument Lane, Toton, Watford, Chester and Reading. She ended her BR career on the Western Region, based at Laira and working services on the Kingswear branch, before withdrawal in December 1972.
The Class 103 has fared badly in preservation — asbestos contamination in the underframe insulation saw most examples scrapped, and only three vehicles are known to survive today. 50413 was rescued for preservation by the West Somerset Railway, and her companion trailer, DTCL No. 56169, followed a similar path via the West Somerset Railway and the Diesel & Electric Preservation Group before both vehicles were acquired for Helston in the mid-2000s, arriving via a spell in store at Gwinear Road.
