The London Midland and Scottish Railway (LMS) introduced a number of railcars to service between 1933 and 1939. Most were single units but one was a three-car articulated set.
The LMS bought three four-wheel diesel railcars from Leyland in 1933. They were numbered 29950–29952 in the multiple unit section of th LMS carriage number series. Each had a 95 hp (71 kW) diesel engine. After trials between Preston and Carlisle they worked from Blackburn to Spring Vale and Clitheroe and subsequently at Hamilton Central in Lanarkshire. They passed to British Railways when the LMS was nationalised. BR withdrew them in 1951, so they never received TOPS classification.
An Armstrong Whitworth diesel-electric railcar operated a luxury 12-seat express service on the LMS for two weeks in 1933 between London and Castle Bromwich near Birmingham in connection with a British Industries Fair. This car, with body work by Cravens which incorporated a kitchen, was powered by a standard Armstrong-Saurer 250 bhp engine.
In 1937 the LMS decided to produce a more modern diesel train for itself. This was a three-car articulated railcar that was outshopped from Derby Carriage and Wagon Works in 1939. The cars were numbered 80000, 80001 and 80002.
The streamlined three-car train was a single articulated unit; the two outer coaches were each 64 ft (19.51 m) long and rested on a centre coach that was 52 ft (15.85 m) long. The articulation was an idea that had been already taken up by Sir William Stanier for some locomotive hauled stock.
Mechanically the train was a development of railcars that had entered service from 1933 on the LMS Northern Counties Committee's (NCC) lines in Northern Ireland, using an identical arrangement of in-line powertrain as NCC railcars Nos. 2–4. Under each coach were two vertically mounted Leyland 125 bhp (93 kW) diesel engines driving the inner axle of each bogie through a Lysholm-Smith torque converter. There were six engines for the three-car set which gave a total power of 750 bhp (559 kW). The whole unit weighed 73 long tons, so this yielded a power/weight ratio of slightly more than 10 bhp/ton which provided a main line standard of performance with a maximum speed of 75 mph (121 km/h).
It worked first on the Varsity Line between Oxford Rewley Road and Cambridge, and then on St Pancras – Nottingham services. A second unit was planned but never built. 80000–80001–80002 was withdrawn on the outbreak of World War II in 1939, stored, and never re-entered passenger service.
In 1949 BR converted the articulated unit to a two-car set for overhead line maintenance. The centre car was removed and the number of engines in the set reduced to two. The driving cabs were given flat ends. To enable engineering staff to work on the overhead cables the roofs of the two coaches were flattened, creating a work space 130 feet (40 m) long and 5 feet 4 inches (1.63 m) wide. Between the two cars a manually-operated lift was installed that could be raised to 6 feet (1.8 m) above roof level.
One coach was converted into a workshop with all passenger seats removed and workbench facilities installed. The other coach was converted into staff accommodation with lockers, cooking, washing facilities and a WC, and 12 seats with tables as a mess saloon. An old 30 feet (9.1 m) coach was converted to carry 2,000 feet (610 m) of overhead wire and attached to the unit as a trailer. Portable floodlights for night work were installed in the two coaches and in the trailer.
The unit worked on the Manchester – Altrincham line. TIt was moved to Longsight Depot in 1959 and taken out of service shortly afterwards. It still existed in a derelict state as late as 1967.
The design may be seen as a step in the development of post-war British Railways diesel multiple units (DMU) such as the Derby Lightweight units, at least as far the powertrain is concerned.