British Rail Class 27

Original allocations were D5347–D5369 to Glasgow Eastfield, D5370–D5378 to Thornaby and D5379–D5415 to London Cricklewood for Tilbury Boat trains and Cross-London freight services. In the period September to December 1963, some of the Cricklewood allocation were transferred to Leicester and in December 1965 the Thornaby allocation was also nominally transferred to Leicester to join them. Traffic changes combined with reallocation of Class 25s led to the gradual transfer of the Leicester and Cricklewood locomotives to Scotland during 1969 thus concentrating the whole class within Scotland and being part of the replacement fleet that allowed the withdrawal of the poorly performing Clayton Class 17 locomotives from traffic. For many years they were extensively used on the West Highland Line.

By September 1986, the final vacuum brake only locomotives had been withdrawn, regular duties on passenger services had ceased and only twenty-one of the class remained, allocated entirely to Eastfield depot. A mass withdrawal in July 1987 due to the presence of blue asbestos left 27008 as the last in service. Its final working was on 13 August and the loco was officially withdrawn on 19 August 1987. The Class 27s were actually outlived by the older Class 26s, whose less powerful engines were more reliable.

• 27/0: Locomotives as built with steam heating (excluding 27024–27031)
• 27/1: Locomotives converted in 1971–1973 for push pull operation, renumbered back to 27/0 after conversion starting in 1982.
• 27/2: Locomotives converted in 1973–1976 with Electric Train Heat, renumbered back to 27/0 after conversion starting in 1982.

By the late 1960s, the Swindon-built Inter City DMUs operating the Edinburgh Waverley - Glasgow Queen Street express service were becoming unreliable. In 1970 the decision was made to replace them with locomotive-hauled carriages. So between 1971 and 1973, twenty-four Class 27s were fitted-up with dual (vacuum and air) brakes and reclassified Class 27/1, while 36 Mark 2 carriages (7 brake second opens, 22 open seconds, and 7 corridor firsts) swapped their vacuum-operated shoe brakes for air-operated disc brakes and were though-wired with "Blue Star" control cables to enable "top and tail" push-pull working. It was later decided that as the Mark 2 stock was dual (steam or electric) heated, to convert half the 27/1 fleet to electric train heat, by replacing the train heating boiler with a Deutz 8-cylinder, air-cooled diesel engine and alternator. The conversions were then classified as Class 27/2, and were used on one end of the train, with a 27/1 on the other.

The very intensive 90 mph (140 km/h) "push-pull" service was demanding on the locomotives and reliability started to suffer. The 27/2s, especially, appeared prone to fire damage, especially from their electric train heating alternators. The push-pull sets were replaced in 1980 by single Class 47/7s at one end of a rake of Mark 2 carriages and a DBSO. The Class 27/1s and 27/2s were then renumbered to 27/0 and could often be found on Edinburgh-Dundee semi-fast passenger services, until their replacement, briefly by Class 101 and subsequently by Class 150 Sprinter DMUs in 1987, whilst the remainder were largely used on freight.

• On 30 June 1962, locomotive D5386 was in a minor collision with a diesel multiple unit at Cricklewood carriage sidings, London due to confusion over a hand signal. The engine is now preserved and stored at Barrow Hill Roundhouse.^[3]
• On 25 August 1965, locomotive D5383 was heading a freight train that collided with the rear on another freight train at East Langton. It was taken to Derby Works for evaluation, but was withdrawn in January the following year.^[4]
• Locomotive 27 044 was severely damaged by fire before 5 September 1980. It was consequently withdrawn and scrapped.^[5]

Eight examples of the class have been preserved at various heritage railways in Great Britain.^[9] Two members of this class were rescued from Vic Berry's Scrapyard in the 1980s. D5410/27059 was rescued from Vic Berry's Scrapyard in September 1987 ^[10] and D5401/27056 was also rescued from there in October 1987.^[11]

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  27001 at the Bo'ness and Kinneil Railway
•  
  27066 on the Dean Forest Railway
•  
  D5401 (27056) at the Great Central Railway

During the 1980s, Minitrix produced Class 27 models in British N gauge. In 2013, Dapol introduced DCC-ready models of 27032 in BR blue and D5356 in BR green, also in British N gauge.^[12][13]

• Harris, Roger (1985). The Allocation History of BR Diesels and Electrics (2nd ed.). Bromsgrove: Roger Harris.
• Marsden, Colin J. (1981). Motive power recognition:1 Locomotives. Shepperton: Ian Allan Ltd. ISBN 0-7110-1109-5.
• Oakley, Michael (1981). BR Class 26/27 Diesels. Truro: D Bradford Barton. ISBN 0-85153-418-X.
• Strickland, David C. (September 1983). Locomotive Directory: Every Single One There Has Ever Been. Camberley: Diesel and Electric Group. ISBN 978-0-906375-10-5. OCLC 16601890. OL 27959920M. Wikidata Q105978499.
• Tayler, A.T.H (1984). BR Locomotives:2 Sulzer Types 2 and 3. Ian Allan Ltd. ISBN 0-7110-1340-3.
• Webb, Brian (1978). Sulzer Diesel Locomotives of British Rail. David & Charles. ISBN 0715375148.
• Williams, Alan; Percival, David (1977). British Railways Locomotives and Multiple Units including Preserved Locomotives 1977. Shepperton: Ian Allan Ltd. ISBN 0-7110-0751-9.
• Ian Allan ABC of British Railways Locomotives, 1983 edition

• Marsden, Colin J.; Fenn, Graham B. (1988). British Rail Main Line Diesel Locomotives. Sparkford: Haynes. pp. 112–117. ISBN 9780860933182. OCLC 17916362.
• Vehicle Diagram Book No. 100 for Main Line Diesel Locomotives (PDF). Derby: British Railways Board. October 1984. pp. 14–15, 35, 69–77 (per pdf) – via Barrowmore MRG.
• Warner, Alan (2012). The Deadman's Pedal. Jonathan Cape. ISBN 978-0-224-07170-3.
• Kerr, Fred (May 1984). "Short and snappy". Rail Enthusiast. EMAP National Publications. pp. 23–27. ISSN 0262-561X. OCLC 49957965.
• Clough, David (October 1986). "A Tale of Two Scotties — the BCRW Classes 26 and 27". Rail Enthusiast. No. 61. EMAP National Publications. pp. 36–39. ISSN 0262-561X. OCLC 49957965.

• Scottish Railway Preservation Society home to 27001 and 27005
• Mid Hants Railway home to 27007
• Caledonian Railway Diesel Group, owners of 27024
• Owners of 27056 based at the Great Central Railway
• Severn Valley Railway home to 27059
• Owners of 27066 based at the Dean Forest Railway