The British Rail Class 55 is a class of diesel locomotive built in 1961 and 1962 by English Electric for British Rail. They were designed for the high-speed express passenger services on the East Coast Main Line (ECML) between Edinburgh and London King’s Cross. They gained the name “Deltic” from the prototype locomotive, DP1 Deltic (the running number DP1 was never carried), which in turn was named after its Napier Deltic power units.

Twenty-two locomotives were built, which dominated express passenger services on the ECML, particularly from London to Leeds and Edinburgh, until 1978 when Class 43 High Speed Trains (HSTs) were introduced. They were subsequently relegated to semi-fast services on the Kings Cross to York, Edinburgh and Hull routes and continued on sleeper services along the ECML. Other occasional destinations, although with no officially diagrammed work, included Cleethorpes, Stockport, Liverpool Lime Street and Aberdeen. They rarely worked to Skegness and Scarborough. Other very unusual destinations included Bridlington, Leicester and a BR “Merrymaker” trip to Fort William. They could be found on diversionary routes such as Newcastle to Edinburgh via Carlisle and Doncaster to Peterborough via Lincoln and Spalding, rarely Cambridge although arriving at Kings Cross via Hertford was not unusual. During the latter years, organised Railtours took them further afield to Worcester, Cardiff, Bognor Regis, Dover, Norwich and Exeter. All were withdrawn from service between January 1980 and December 1981.

Three were retained for a few days, until 2 January 1982, to work the farewell special, all being withdrawn immediately on arrival back at York. Six locomotives entered preservation during 1982 and 1983: one by the National Railway Museum, three by the Deltic Preservation Society and two by the Deltic 9000 Fund. Two cabs were also privately purchased.

Further information from Wikipedia

Type and origin
Power typeDiesel-electric
BuilderEnglish Electric at Vulcan Foundry
Build date1961–1962
Total produced22
 • UICCo′Co′
 • CommonwealthCo-Co
Gauge4 ft 8 12 in (1,435 mm) standard gauge
Wheel diameter3 ft 9 in (1.143 m)
Wheelbase58 ft 6 in (17.83 m)
Length69 ft 6 in (21.18 m)
Width8 ft 9 12 in (2.68 m)
Height12 ft 10 in (3.91 m)
Loco weight99 long tons (101 t; 111 short tons)
Fuel capacity900 imp gal (4,100 l; 1,100 US gal)
Prime moverNapier Deltic D18-25, × 2
GeneratorEnglish Electric DC generator
Traction motorsDC traction motors
TransmissionDiesel electric
MU workingNot fitted
Train heatingSteam; later Electric Train Heating
Train brakesVacuum; later Dual (Air and Vacuum)
Performance figures
Maximum speed100 mph (161 km/h)
Power outputEngines: 1,650 bhp (1,230 kW) × 2
Tractive effortMaximum: 50,000 lbf (222 kN)
Continuous: 30,500 lbf (136 kN)@ 32.5 mph (52.3 km/h)
OperatorsBritish Railways
NumbersD9000–D9021; later 55022, 55001–55021
Axle load classRoute availability 5
Preserved55022 (D9000), 55002 (D9002), 55009 (D9009), 55015 (D9015), 55016 (D9016) and 55019 (D9019) Cabs from 55008 (D9008) and 55021 (D9021) also preserved
DispositionSix preserved, remainder scrapped