BR Class 503

British Rail Class 503 trains were 65 mph (105 km/h) electric multiple units. They were introduced in two batches. The first were in 1938, by the London, Midland and Scottish Railway (LMS) with a further batch (built to a similar design) in 1956 by the then nationalised British Railways (BR). When introduced by the LMS, they were officially known as Class AM3. They were designed for, and operated on, the Wirral & Mersey lines from Liverpool to West Kirby, New Brighton, and Rock Ferry. There were few places on their network of closely spaced stations to attain their maximum speed, except for the open section between Moreton and Meols. All but one set were withdrawn and scrapped by 1985. The final set was used on special Merseyrail services until 1988, and this preserved set was kept at the Electric Railway Museum near Coventry until moved to the Locomotive Storage Ltd warehouse at Margate.

Preservation
A single set, formed of vehicles 28690, 29720 and 29289, was earmarked for preservation. Though never carried on the unit, the set was numbered under the BR TOPS code as 503 019. This was the last of the units built in 1938 to have been brought into service. The unit is also one of the only two pre-war main line EMUs in existence, which are still in original formation. The other being the 2-BIL belonging to the National Railway Museum.undefined

The set was kept in serviceable condition and operated occasional special trains on the Merseyrail network until 1988. During this period, the set was used for the opening of the electrified line between Rock Ferry and Hooton on 30 September 1985 and for special services during Christmas 1985.undefined At the same time, Merseyrail decided not to preserve a second set, due to a lack of spares.undefined Following this, the surviving set participated in the Merseyrail 100 celebration on 6 April 1986.undefined The unit, named Ivor T. Davies G.M. on 14 March 1988,undefined was purchased by Wirral Borough Council in 1991 and stored at Kirkdale until 1996.undefined

Two parts of the set were then sold and kept at Steamport, Southport.undefined Meanwhile, the Driving Trailer coach (DTS) was kept at the Wirral Transport Museum.undefined The two parts of the unit, which were sold, have been owned by the Suburban Electric Railway Association since purchase by its forerunner, the Mersey and Tyneside Electric Preservationistsundefined in 1996, and were stored at the Electric Railway Museum on the outskirts of Coventry. After transport of the Driving Trailer coach from Birkenhead, the entire unit was correctly reformed at the Coventry museum in October 2010, for the first time in over 20 years.undefined The Driving Motor coach (DMBS) interior was open to the public during museum open days.

In 2017, the Electric Railway Museum announced that it would be forced to close and relocate its collection. The Class 503 set was moved in May 2018, to the Locomotive Storage Ltd facility in the former Hornby Railways warehouse in Margate.undefined