During the 1980s, British Rail (BR) was interested in replacing its first generation diesel multiple units, particularly in the use of railbuses to service its lightly used branch lines.

By the beginning of the 1980s, British Rail (BR) operated a large fleet of first generation DMUs, which had been constructed in prior decades to various designs.

[9] While formulating its long term strategy for this sector of its operations, British Rail planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these ageing multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos.

[7] In the concept stage, two separate approaches were devised, one involving a so-called railbus that prioritised the minimisation of both initial (procurement) and ongoing (maintenance & operational) costs, while the second was a more substantial DMU that could deliver superior performance than the existing fleet, particularly when it came to long distance services.

[7] While the more ambitious latter requirement would ultimately lead to the development of the Class 150 and the wider Sprinter family of DMUs, BR officials recognised that a cheaper unit was desirable for service on the smaller branch lines that would not be unduly impacted by lower performance specs or a high density configuration.

[10] Initial testing with the Class 140 uncovered several issues, such as difficulty detecting the type via track circuits, this was reliably resolved by swapping the material of the brake blocks from a composite to iron.

Unlike these later siblings, the Class 141 had a noticeably narrower body, having equal width to that of the standard bus; subsequent production models expanded this to maximise internal volume.

[7] Furthermore, in order to maximum cost savings, the manufacturers made use of road bus-standard electrical equipment, passenger fittings, and general cab layout wherever possible.

They were sponsored by West Yorkshire Passenger Transport Executive, and were painted in the PTE's Verona green and buttermilk livery with MetroTrain branding.

[7] Beyond the pursuit of greater reliability, experiments were conducted into areas of enhancement such as ride comfort; one unit was refitted with a wider spring base and double dampers; both of these features were later deemed necessary to provide sufficient levels of performance and were applied to all Class 141s.

Amongst other changes, the unit was re-gauged to metre gauge, and was different from the 20 British trains having only longitudinal seating for 120 passengers and space for another 140 standing.

[citation needed] Following the end of their career with British Rail, 12 Class 141s were sold to Islamic Republic of Iran Railways and were exported during 2001/2002.