the british rail (br) class 310 is a slam-door, alternating current (ac) electric multiple unit (emu) introduced in 1966 as part of the west coast main line electrification project. they were initially classified as class am10 units before the introduction on the tops classification system. constructed at br's derby carriage and wagon works. they consisted of four carriages - a second class driving trailer, a second class trailer, a second class motor car (with guard's/luggage compartment above which the pantograph was mounted) and a composite (1st and 2nd class) driving trailer. the maximum speed was 75 miles per hour. a glass partition behind the driver's cab enabled passengers in the leading and rear coaches to have an excellent view of the line ahead or behind.