British Rail Class 503

The British Rail Class 503 trains were 65 mph (105 km/h) electric multiple units introduced in two batches, the first in 1938 by the London, Midland and Scottish Railway, which called them Class AM3, and a further batch of similar design in 1956 by British Railways. They were designed for the Wirral and Mersey lines from Liverpool to West Kirby, New Brighton and Rock Ferry. Contractors in Birmingham built them, Metro Cammell of Saltley the motor coaches and Birmingham RC&W of Smethwick the underframes, with traction motors supplied by British Thomson-Houston. They were the first electric trains on the main British railway system with air-operated power doors. The majority were progressively withdrawn from June 1984, and the final service train ran on 29 March 1985.