[5] In 1955, British Rail published a Modernisation Plan to streamline the railway network, bringing it up to date in comparison to European standards.

[6] BR hoped that by replacing steam with DMUs, costs would be reduced sufficiently to make rural lines viable.

[7] Since there was no time for BR to issue a standard specification, train builders were invited to submit plans on the understanding that the units could be built and put into service quickly.

Having gained experience with early lightweight DMUs, Metro Cammell won a contract and put the Class 101 into production.

[8][failed verification] Metro-Cammell advertised their new train highlighting the wide availability and modern features the 101 offered.

[10] The 101s came in two, three or four car units, with two driving carriages one or two of which were powered by 11.3 litre BUT six cylinder diesel engines with epicyclic gearboxes.

[16] Upon ScotRail's formation, the units continued in use and were in service up to Privatisation in 1997, with some painted in orange and black Strathclyde PTE livery.

[citation needed] In January 1984, a fire at Ayr depot destroyed six 101s and as a result an equivalent number of Class 104 were drafted in to fill the gap.

Just as with the Class 116 which was also heavily used on the same routes, the 101s were withdrawn from WMPTE service on 12 July 1993 when the Cross-City Line was fully electrified.

Later services were run by Tyne and Wear Passenger Transport Executive and stabled at South Gosforth depot.

[citation needed] At which point, the class was withdrawn and the sets sent to Neville Hill depot in Leeds to be re-deployed.

[25] Several 101s received Network Southeast branding and by the early 1990s had been scaled back to running local services between Didcot, Oxford and Bicester.

[31] However, with the electrification of the region and introduction of newer rolling stock, by the early 1990s they had fallen out of favour and were re-allocated to other parts of the rail network.

Despite the intention to phase out the type and other Heritage DMUs in favour of newer stock, the 101 proved to be a dependable workhorse.

At this point, they were repainted in Regional Railways livery, and had the class number applied concurrently with several Sprinter and Pacer sets.

[33] Along with other first generation types, corrosion of the body panels and asbestos used during construction was seen as major concerns and were leading causes for their eventual retirement.

[35] It was intended to phase the 101s out of service in favour of the Class 142 in the late 1990s, but the Privatisation of British Rail delayed those plans.

[citation needed] Following privatisation the remaining 101 sets in mainline service fell under the ownership of Angel Trains and operated by the First North Western franchise once the units from Scotland had been returned to Manchester.

[37] The 101 was seen regularly running on the North Wales Coast Line service between Crewe and Holyhead alongside loco hauled trains as late as 1999.

[41] Because of the type's popularity and longevity in service, a final farewell tour for the 101s was run in late 2003 which was a railtour of northwest England.

[48] Lima also produced a Class 101 for a number of years, in Green, Blue/Grey, Regional Railways and Network Southeast liveries.

W. Awdry, and the adapted television series Thomas the Tank Engine and Friends, although Daisy is a single car.