The British Rail Class 502 was a type of electric multiple-unit passenger train, originally built by the London, Midland and Scottish Railway at its Derby Works.

In addition the 502s had distinctive large resistance cooling grids mounted on top of the cab roof of the motor units.

Virtually all electric suburban passenger trains in Great Britain now follow the basic layout pioneered by the Class 502s and 503s, with two sets of double-leaf air operated sliding doors on each side of each carriage.

Stabling points were also situated outside Southport Chapel Street station and at Bank Hall,[10] to the west of the four live running tracks.

The Bank Hall stabling point fell into disuse prior to the Loop and Link extensions of the 1970s and was replaced by Kirkdale depot in 1976.

The 6-car sets were formed with motor cars at the outer ends of the formation with the driving trailers coupled together in the centre.

As initially built there was considerable overprovision of first class accommodation, which usually ran virtually empty on these routes.

When BR changed their liveries in the mid-1960s the units were repainted plain Rail Blue, continuing with the small yellow warning panel and eventually gaining full yellow ends, the white 'double arrow' British Rail symbol was carried on the DMBS only, continuing the tradition of the green livery of only carrying the BRITISH RAILWAYS symbols on motor coaches.

Towards the end of their life, in the late 1970s, they were repainted again in their first two-tone livery, the standard blue and grey, in which scheme they were withdrawn.

For many years the unit was kept at the Steamport centre in Southport, where it was restored to original LMS condition, complete with maroon livery.

However, when Steamport closed, the NRM were unable to find an alternative location to display it, and relocated the unit to remote storage at MoD Kineton.

In early 2007, it was suggested that the NRM was considering disposing of this unit as it no longer featured as part of its long-term plans.

[24] In March 2012, following re-development of the site, the unit was moved to the base of the Merseyside Transport Trust in Burscough, Lancashire.