The original London and North Western Railway locomotive shed in Bletchley was a wooden and galvanised iron building that catered for some twelve engines, with three roads accommodated within the facility.^[2] However during the 1870s the shed collapsed in a gale, burying stabled locomotives and was replaced by two gabled roof spans with numerous ducts and chimneys.^[2] When newly rebuilt, it would measure 250 feet (76 m) in length, with a maximum width of 100 feet (30 m).^[2] These sheds were situated just north of the railway station on a siding to the west side of the West Coast Main Line, on a site now occupied by today's carpark.^[2]

Towards the end of the 19th century, a number of LNWR Lady of the Lake class steam locomotives were employed as pilot engines, with ‘Bletchley Shed’ as their home depot  – by then considered an intermediate Loco Shed.^[2] The end of British Rail steam in Bletchley came on Monday, 5 July 1965 when 24 steam engines stabled in the Locomotive Shed departed for other parts of the country, the last one taking the 2pm parcels train to Oxford.^[2] This was locomotive No. 48610 LMS Stanier Class 8F 2-8-0, which had been stabled at Bletchley for ten years.^[2] With the end of steam, the TMD was relocated to the Bedford side of the Varsity line flyover, in a new purpose built facility.^[2]

Bletchley TMD began in the modern era in 1965 (though it had existed since 1850, in the age of steam).^[3] It closed on 30 June 2008 and its (expired) lease returned to Network Rail.^[3] Bletchley had won awards for the reliability of its trains as recently as March 2007, and was said to deliver six times better than average reliability.^[4] London Midland phased in the fleet of 37 Class 350/2 Desiro trains, which are maintained by Siemens at the Kings Heath Depot in Northampton. These replaced the Silverlink Class 321 fleet which had been serviced at Bletchley.^[3] Most of the engineers & technicians transferred to the Siemens site and the cleaners to London Midland.^[3] Local press expressed concern that maintenance of the trains being used on the Marston Vale Line was being transferred to Tyseley TMD in Birmingham, with consequent long delays to service resumption in the event of train failure.^[5][6]

Bletchley depot was bought back into use by Vivarail in September 2018 to maintain its Class 230 diesel units.^[7] These were used exclusively on the Marston Vale Line until the company failed and the trains were withdrawn in December 2022.^[8]

In July 2023, three British Rail Class 150 were transferred to Bletchley TMD, in preparation for their introduction to service on the Marston Vale Line.^[9]

In April 2024, West Midlands Trains announced that it had placed a £66M contract to upgrade the depot. When completed in autumn 2025, Bletchley TMD will "become the principal maintenance base for WMT’s newly procured Class 730 Aventra fleet".^[10]

• List of British Railways shed codes

• S.K. Baker (4 April 2024). Rail Atlas Great Britain & Ireland. Oxford Publishing Company. ISBN 978-0-86093-553-7.