The British Rail Class 104 diesel multiple units were built by Birmingham Railway Carriage and Wagon Company from 1957 to 1959.

A product of British Rail's Modernisation Plan of 1954,^[2] the 104s were designed for general branch line and commuter routes.^[3] The first units ordered were for the London Midland Region, with the majority of the class for use in North West of England. The Class 110 was a re-engineered version of the 104 with more powerful engines, but did not last as long in service. The 104s had asbestos insulation removed during the 1970s.^[4]

• BR Blue-liveried Class 104 in the snow, Buxton (Derbyshire) 24 December 1978
• Class 104 at Castleton station
  29 September 1982
• Unit EXP.DM.352. at its home depot of Longsight Diesel TMD, Manchester, 15 January 1984

• On 18 January 1986, a Class 104 unit (vehicles 53433 & 53482) suffered a brake failure, ran past three signals at danger and collided with Class 47 locomotive 47 111 near Preston. Forty-four people were injured.^[9]

A number of Class 104s were used following their withdrawal from passenger services.

The last two London Midland DTCL vehicles to survive, M54182 & M54183, were converted in 1987/1988 into loco hauled Sandite cars and renumbered ADB977554/ADB977555 respectively.^[10] Used until 1994, M54183 was scrapped in February 1994^[11] while M54182 was stored at Buxton until June 2000 and was saved for preservation.^[12]

Other Sandite cars included 53472, 53478 & 53530 which were used in Scotland until April 1989.^[10]

Derby RTC, known for their railway testing, used 53475, 53506 & 53422 (renumbered 977342, 977343 & 977344 respectively) as carriage washing test coaches. They also used 53451 & 53529 as part of DMU auto-gear experiments until February 1991.^[10]

M54182 was the only vehicle converted for non-passenger use to survive into preservation.^[11] In 2008 after several years in storage, the vehicle was restored externally, retaining its departmental condition and run in a demonstration capacity with Class 37 37075 for a gala weekend at the Churnet Valley Railway.^[12] It was believed by the organisers to be the first and only time that departmental DMU Sandite operations had been recreated in a heritage setting.

13 Class 104 vehicles are preserved, all were owned privately by two individuals.^[13] 12 vehicles were preserved in 1992 in a bulk tender from British Rail who at the time were reluctant to sell individual vehicles or sets.^[13] The thirteenth was saved in 2000 after protracted storage after departmental use. In 2020 the first one was scrapped (50556) due to its extremely poor condition at the East Lancashire Railway.^[12]