British Rail Class 15

The British Rail Class 15 diesel locomotives, also known as the BTH Type 1, were designed by British Thomson-Houston, and built by the Yorkshire Engine Company and the Clayton Equipment Company, between 1957 and 1961. They were numbered D8200-D8243.
==History==
Following the British Railways Modernisation Plan, ten of the class were ordered for evaluation under the 'pilot scheme'. Like other locomotives designed to the 'Type 1' specification, they were intended for use on local freight and empty coaching stock trains.
===Construction===
The design and manufacture was a collaboration between several companies. BTH (the main contractor) provided electrical equipment, Paxman supplied the power units, and Clayton supplied bogies and superstructure, with the frame construction and final assembly taking place at Yorkshire Engine's Sheffield works. These ten locomotives, numbered D8200–D8209, entered service between November 1957 and November 1958.
The design showed sufficient promise for a repeat order for 34 more locomotives to be placed soon afterwards. These locomotives, numbered D8210–D8243 and built by Clayton at Hatton, Derbyshire, were delivered between October 1959 and February 1961.
===Service===
The first ten locomotives were delivered to the London Midland Region's Devons Road depot in Bow, East London, where they were evaluated against the contemporary North British Type 1 and English Electric Type 1 designs. Soon, however, the entire class was allocated to depots on the Eastern Region, where they remained until withdrawal. The second block of ten was originally allocated to March depot in East Anglia, however due to the Clean Air Act 1956 the locomotives were quickly re-allocated to East London, allowing the replacement of steam locomotives in that area. Thereafter, the type was allocated exclusively to Stratford, Finsbury Park and Ipswich depots.
===Accidents and incidents===
On 21 November 1963, locomotive No. D8221 crashed through buffers whilst shunting at Ipswich, Suffolk and ended up across Croft Street. After attempts to tow it back onto the track using diesel locomotives failed, it was retrieved using the only steam locomotive in service at Ipswich, which had been retained for carriage heating purposes.
===Problems===
The class were troubled by several reliability problems, notably with the engines which were found to require excessive maintenance. A series of modifications to the pistons, piston rings and maintenance schedules, and fitting cast iron cylinder heads improved the engine reliability considerably, but a complex V16 for only 800 bhp and a small class size doomed them with a contracting rail network. The layout, with a single cab positioned part-way down the body like a North American road-switcher, gave the crew poor forward visibility in both directions of travel, although this was initially tolerated as it was no worse than the visibility from a steam locomotive cab. Despite these problems the class were more successful than the contemporary Type 1 locomotives of Class 16 and the later Class 17.
===Withdrawal===
With a decline in freight duties in the London area, and as a relatively small, non-standard and unreliable class, the type was considered surplus to requirements by the late 1960s. All were withdrawn from capital stock between April 1968 and March 1971.
==Conversion==
All but four had been broken up for scrap by the end of 1972. The four that survived were converted into non-powered electric train pre-heating units at Doncaster Works, these duties keeping the locomotives employed for another ten years or more, until they were again made redundant and withdrawn.
==Preservation==
One of the former train heating units, D8233, was purchased for preservation in 1984 and is now the only survivor of the type. It was originally kept at the South Yorkshire Railway in Sheffield, moving in 1986 to the East Lancashire Railway, and in 1988 to the Mangapps Farm Railway, where it remained until 1993. D8233 then moved to Crewe following an agreement with the Waterman Heritage Trust. Since its initial preservation the locomotive had received little work apart from cosmetic attention. Some work was carried out by the Waterman Heritage Trust, however the locomotive's restoration remained dormant until the end of 2005, when a reformed owning group, alongside the WHT, agreed the time was right to accelerate the locomotive's return to service. With an active plan for work agreed, the locomotive returned to the East Lancashire Railway in February 2006, where its restoration to working order is now under way.
== Gallery ==
File:D8233Wiki.jpg
Category:Locomotives
Category:British Rail locomotives
Category:1955 Modernisation Plan
Category:Four-axled diesel locomotives
Category:B-B locomotives
Category:Diesel locomotives
Category:British Thompson-Houston locomotives
Category:Yorkshire Engine locomotives
Category:Clayton locomotives
Category:Non-Standard Locomotives
Category:United Kingdom
Category:Built in 1957
Category:British Rail diesel locomotives
Category:Sole survivor