British Rail Class 37

English Electric Type 3 British Rail Class 37
37409 and 37229 pass Dawlish Warren en route to Penzance
Power type	Diesel-electric
Builder	English Electric at Vulcan Foundry and Robert Stephenson and Hawthorns
Build date	1960–1965
Total produced	309
Configuration	Co-Co
UIC classification	Co'Co'
Gauge	4 ft 8 1⁄2 in (1,435 mm) Standard gauge
Wheel diameter	3 ft 9 in (1.143 m)
Minimum curve	4 chains (80 m)
Wheelbase	50 ft 8 in (15.44 m)
Length	61 ft 6 in (18.75 m)
Width	8 ft 10 1⁄2 in (2.71 m)
Height	12 ft 9 in (3.89 m)
Locomotive weight	100 long tons (102 t) to 105 long tons (107 t) except 37/7 and 37/9 class - ballasted to 120 tonnes
Fuel capacity	890 imp gal (4,000 l; 1,070 US gal) increased to 1,690 imp gal (7,700 l; 2,030 US gal) on rebuild
Prime mover	Built: English Electric 12CSVT 37/9: Mirrlees Blackstone MB275Tt or Ruston RK270Tt
Generator	Original: Main: English Electric EE822, Aux EE911/5C Rebuilt locos: Main: Brush BA1005A alternator, Aux: Brush BA606A
Traction motors	English Electric
Transmission	electrical (DC traction motors)
Multiple working	★ Blue Star
Top speed	90 mph (140 km/h)
Power output	Engine: 1,750 bhp (1,305 kW)
Tractive effort	Maximum: 55,500 lbf (247 kN) Continuous: 35,000 lbf (156 kN) @13.6 mph (22 km/h)[1]
Train heating	37/0: Steam 37/4: Electric Train Heat Remainder: None
Locomotive brakeforce	50 LTf (498 kN)
Train brakes	Vacuum, Dual, or Air
Career	British Rail DB Schenker DRS West Coast Railway Company
Number	D6700–D6999, D6600–D6608; later 37001–37308
Nicknames	Tractor, also Syphon, Growler or Slugs
Axle load class	Route availability 5 except subclass 37/7 RA 7

The British Rail Class 37 is a diesel-electric locomotive. Also known as the English Electric Type 3, the Class was ordered as part of the British Rail modernisation plan.

The Class 37 became a familiar sight on many parts of the British Rail network, in particular forming the main motive power for Inter-City services in East Anglia and within Scotland. They also performed well on secondary and inter-regional services for many years. The Class 37s are known to railway enthusiasts as "Tractors", a nickname derived from the similarity of the sound of the locomotive. 37 093 was the "police" locomotive which pulled over a Class 43 HST power car for speeding in the "Intercity 125" advert from the 1980s.

Description

Background

As part of the large scale dieselisation brought about by the British Rail modernisation plan a need was identified for a number of type 3 locomotives of power output 1,500 hp (1,100 kW) to 1,999 hp (1,491 kW). English Electric had already been successful with orders for type 1 and type 4 diesels, and had produced locomotives of similar power to that which was required for railways in East Africa. A design based on the exported locomotives was put forward and accepted. The design was for a general purpose locomotive and initially found service in British Rail's Eastern Region.

Building

The Class 37 locomotives were built in the late 1950s and early 1960s, the order split between English Electric's Vulcan Foundry at Newton-le-Willows, and Robert Stephenson and Hawthorns of Darlington. 309 locomotives were produced in total, originally numbered in the range D6700-D6999 and D6600-D6608. The bodywork bears a strong family resemblance to other English Electric designs such as the Class 40 and Class 23 'Baby Deltic'.

Duties

The class was designed for both passenger and freight work and was as much at home hauling heavy goods trains as it was on passenger services (indeed, in 1966 the Western Region even tried modifying some of its 37s for 100 mph (160 km/h) operation). Many of the original locomotives were fitted with boilers for steam heating. With the withdrawal of many Type 2 and Type 3 locomotives in the 1980s the 37s were selected as the standard Type 3 and many of the fleet were given a heavy overhaul to prolong their life into the 1990s and beyond. Some were fitted with electrical train heating (ETH) equipment in the 1980s to become the 37/4 sub-class, initially for use on the West Highland Line and Far North lines but later seeing use in other parts of the country.

Rebuilding

A number of locomotives were rebuilt as Class 37/9 in the late 1980s to evaluate Mirrlees and Ruston engines for possible use on a new Class 38 freight locomotive. These 'Slugs' were heavily ballasted to improve traction and had excellent load-hauling capabilities, but the Class 38 (understood to be a 'modular' locomotive based on the approach that gave rise to the Class 58 and the unbuilt Class 88 electric loco) was never built.

Axle load

Class 37 Cab 37052

The Class 37 has a relatively low axle loading for its size and power. With the withdrawal of most of the smaller types of diesel locomotive, this left them as the only mainline type available in significant numbers for lines with weight restrictions, and for a number of years they handled almost all locomotive-hauled services on the West Highland Line, the lines north of Inverness (Far North Line) and in parts of Wales. The Class 37 has Route Availability 5 and this is one of the main reasons they are still in use on the network.

TOPS renumbering

As with many diesel classes, the TOPS renumbering was implemented in a straightforward manner, with the locomotive numbers remaining in sequence. Thus 6701 became 37001 and D6999 became 37299; while D6600 - D6608 became 37300 - 37308. The remaining locomotive, D6700 became 37119 instead of D6819 which became 37283. As members of the class were altered later in their careers, they were renumbered, some more than once.

D6983 had been withdrawn in December 1965 following a fatal collision with a derailed Class 47, number D1671, in South Wales, near Bridgend as the result of a landslip. D6983 was the first EE Type 3 to be withdrawn and as a result, the only locomotive in the entire class not to receive a TOPS number. The remains of both locomotives were sold to local scrap merchants R.S. Hayes and cut up the following year.

Sub-classes

In the 1980s the Class 37 locomotives were extensively refurbished - from that point 37/0 refers to the original version. The work took place at BREL in Crewe except for the 37/3 subclass whose bogies were replaced at various depots.

Sub-class	Description
37/0	Locomotives which remained unmodified after other sub-classes were created
37/3	Locomotives which were rebogied but not refurbished
37/4	Refurbished, rewired, English Electric generator replaced with Brush alternator, electric train supply (ETS) fitted
37/5	Refurbished, rewired, English Electric generator replaced with Brush alternator
37/6	Locomotives from Class 37/5 further modified with through ETS wiring and RCH jumper cables
37/7	Refurbished, rewired, English Electric generator replaced with GEC G564AZ or Brush alternator, additional weight added
37/9	Refurbished, rewired, English Electric generator replaced with Brush alternator, new engines: Mirrlees MB275Tt or Ruston RK270Tt

Class 37/0

This designation covered all 309 locomotives as built, but with such a large number of locomotives and with two companies involved in the building, there were several differences within this sub-class alone. The most visible external difference was that the first 119 locos had a "split" headcode box; for these locos the four digit Train reporting number was shown in two square boxes containing two digits and separated by a pair of doors designed to allow the train crew to be exchanged while in motion. Later locomotives had a single centrally placed headcode box, and also had the horns mounted on the roof rather than built into the nose of the locomotive. This difference was the reason for the double change in numbers when implementing the TOPS scheme described earlier.

Class 37/3

These locos were rebogied at various depots with the regeared Cast bogie frame type 'CP7 Bogie' (bogies from the English Electric Deltics, Class 50 and Class 37s are largely intechangeable with only modfication to traction motor gearing and access step positions needing alteration between the classes), the fuel capacity was doubled (by using the redundant train heating boiler water tanks) but no other changes were made.

Class 37/4

EWS maroon 37/4 at Fort William

With ETH (Electric Train Heating) replacing 'steam heated' coaches, some of this class received ETH Supply when refurbished at Crewe Works during 1985 and 1986. During this refurbishment, the locomotives also received regeared CP7 bogies and the English electric generator was replaced with a Brush BA1005A alternator. Extensive re-wiring, as well as a full repaint into BR Large Logo was undertaken. The modifications allowed the 're-built' locomotives to work passenger trains all year round, with the 31 strong fleet being split between Wales and Scotland, Scotland receiving the first 25 and Wales the next six.

After the extensive refurbishment, the locomotives were allocated the 37/4 sub-class, following the trend of renumbering 'ETH' fitted locomotives xx/4s, (e.g. 47 4xx and 31 4xx).

The next chapter saw the entire sub-class pass to Trans-Rail, which was one of the three regional freight operating companies prior to the privatisation of the entire British rail network.

Over the years, the locomotives have received a large number of liveries: BR Green, Regional Railways, Trainload Grey, EWS maroon, Trans-Rail, BR Large Logo and Mainline, to name a few.

The North Wales Coast Line, The Rhymney Valley Line, Fort William and Oban, South Wales Main Line, and the West Country all benefited from the use of 37/4s. They are were operated by EWS and often found use on Railtours and aluminium traffic. EWS used to cycle 37/4s in and out of traffic on a regular basis, depending on demand. All have subsequently been sold to DRS by EWS's successor DB Schenker (see below).

Loco hauled operations have taken a big hit within the past couple of years, thanks to the widespread introduction of diesel multiple units, and the replacement of loco hauled trains by multiple units, although the sub-class did hold out on the Cardiff - Rhymney trains for Arriva Trains Wales latterly. 37411 and 37425 were painted especially to mark the end of loco hauled service on the line in April 2005, these repaints being funded by Arriva.

In Late 2010, DB Schenker put all of its remaining 37/4s up for sale with many examples expected to be sold for scrap. DRS have since bought the remaining class 37/4s as of April 2011.

Class 37/5

This class were updated in similar fashion to the 37/4 subclass, except they did not receive Electric Train Heating and some were fitted with Sandite ports.

Class 37/6

Two 37/6 types

Eurostar (UK) Ltd. (at the time European Passenger Services) had twelve locomotives modified (all ex-37/5) as Class 37/6, with the intention that they would haul overnight international trains ("Nightstar") over the non-electrified sections of their routes in Britain. However, these services were never introduced, and, in 1997, Eurostar sold six of its locomotives to DRS, with a further three sold in 2000. The remaining three locomotives were retained by Eurostar for a variety of tasks, including driver training, route learning, and for rescuing failed Class 373 units. Once Eurostar moved its operations to its new depot at Temple Mills, its Class 37 locomotives became redundant and they were sold to DRS in 2007.

Class 37/7

Load-Haul liveried 37/7 type

The Class 37/7 is a sub-class of the Class 37, intended primarily for heavy freight.

Again, as part of the major refurbishment scheme of the Class 37 locomotives in the 1980s, another freight dedicated fleet of 44 Class 37s was created; the Class 37/7 subclass which was identical to the 37/5 subclass except for the addition of a ballast weight to give extra 'pulling power' when hauling heavy freight trains such as the metals trains in South Wales. Again, like the 37/5s, there were two batches completed; from phase 1 and phase 2 Class 37/0 locos. The batch numbered 37701 upwards were from phase 1 build locos and have the flush front ends and the batch numbered from 37899 downwards were rebuilds from phase 2 locos, having the central headcode box (plated over). A further complication was created; locos numbered 37796-37803 had a different type of electrical equipment fitted as part of a trial and differ from the other locos in the subclass internally.

When EWS introduced its 250 Class 66s from 1998, many of the sub-class were put into store. Some have since been involved in construction work in France and Spain building new high-speed lines. 15 were sent to Spain; an additional two were sent to Italy.

EWS has been selling off the sub-class. Four were purchased by West Coast Railway Company for overhaul and main line charters; these are 37706, 37710, 37712 and 37717. 37717 has since been sold for scrap while 37712 returned to traffic before a serious internal fire. 37706 is now the only operational 37/7 in the UK.

Class 37/9

In 1986, four Class 37s, numbers 150/148/249/124, were converted to test the Mirrlees MB275T engine and Brush alternator for the proposed Class 38, and were numbered 37901-4. These were followed in 1987 by 37905/6, converted from 37136/206, and fitted with the alternative pairing of a Ruston RK270T engine and GEC alternator. All six locomotives were fitted with new bogies, and had ballast weights to increase their overall weight to 120 tons. Although intended as a testbed for the Class 38, the two power units fitted were those considered for the Class 60, which was eventually delivered with an enlarged version of the Mirrlees MB275T.

All six Class 37/9s were delivered in Railfreight Grey livery and operated as part of the British Rail Heavy Metals sector, being based in South Wales and hauling trains normally rostered for the much more powerful Class 56 such as the Port Talbot Steelworks - Llanwern Iron Ore tipplers. During the late 1990s, use of the Class 37/9s declined due to availability of the newer and more powerful Class 66s and problems maintaining such a small number of non-standard locos, with all six officially designated as being in storage in 1999.

This was not, however, the end of the sub-class. In July 2000, 37906 was designated as part of the EWS heritage fleet but has since been sold into preservation, joining 37901 and 37905. 37902 was sold to Direct Rail Services in 2003, but was scrapped and cut up in 2005 after a review by DRS. 37904 was cut up at Booths in Rotherham in November 2004 and 37903 was scrapped at Crewe Diesel TMD in April 2005. As of October 2010, 37906 is still fully functional and in preservation.

Operations

British Rail

During the time of British Rail, the Class 37s found use on both passenger and freight workings, being one of the mainstays of the BR fleet. While freight use was widespread, passenger work was predominantly in the Eastern Region with use on London - Norwich and Cambridge services, the latter through to the 1980s.

In the early 1980s, the remaining steam-heat capable locomotives gravitated to Scotland, replacing both Class 27s on the West Highland Line and Class 26s on the Far North and Kyle lines. The other notable use was of nominally freight locomotives to Aberystwyth over the Cambrian line, in this case taking over from Class 25s on the holiday trains.

Also in the early 1980s, British Railways wanted to test a design for self-steering bogies, for use on the West Highland Line to Fort William and Mallaig. 37175 was used as the test-bed loco and carried what were known as "CP5" bogies for this purpose. The West Highland trials were found to be successful, but to alter or manufacture such bogies on a large scale was deemed unjustified.

From 1985, the 37/4 subclass took over on the Scottish lines although the use of original 37/0s continued in the summer when train supply was not required. The Welsh allocation in turn took over from the 37/0s on the Cambrian as well as from Class 33s on Crewe - Cardiff workings.

Over time they were displaced from most passenger work by new build DMUs such as the Sprinter units, though they still found work in the summer and on secondary services from time to time through the 1990s as traffic demand required. This saw use both on the North Wales Coast and, most remarkably, Cardiff - Rhymney local services through to 2006. The final daily work in Scotland was the Fort William sleeper train, this ending in June 2006.

Their freight work similarly reduced, being displaced by higher powered locomotives such as the Class 56 and Class 58 locomotives on coal trains, though they continued on other cargos such as oil tankers for longer.

Post privatisation

A Class 37 in Spain working for rail infrastructure company GIF

In the 1980s many locomotives were refurbished, which has meant the Class 37 fleet is one of the longest surviving classes on British railways. However, the introduction of new Class 66 locomotives has meant many 37s have been withdrawn or scrapped. EWS (English Welsh & Scottish) and Direct Rail Services operated small fleets, with several other examples also operated by spot-hire companies. However, second-hand Class 37s have also proved popular in the export market, with some examples operating in Spain and France (serving the construction of these countries' high-speed railway networks).

Direct Rail Services

Class 37/0 in DRS livery (1/06/2003)

As of January 2009, Direct Rail Services (DRS) operate around twenty-five Class 37s. They haul nuclear trains, and during autumn have also seen use on sandite trains on behalf of Network Rail. DRS locomotives tend to be used in pairs as a precaution in case one fails en route. Pairs of locomotives have also recently been used on scrap metal trains due to their longer range than the newer Class 66.

DRS also have several more non-operational Class 37s, which are in store, or undergoing overhaul. These locomotives are either at Brush Traction, Carlisle Kingmoor or Crewe Gresty Bridge.

A few of the DRS fleet of Class 37s have yet to return to traffic after being stored due to a lack of OTMR (On-board Train Monitoring Equipment).

DB Schenker (formerly EWS)

No.37423 on the North Norfolk Railway, April 2010

EWS usually used Class 37s in pairs, for freight workings. Additionally EWS used the Class 37s on railtours or charter hire to train operating companies. For example, in 2005 Arriva Trains wales used 37/4 haulage on the Rhymney valley line, from a pool of four locomotives, these locomotives being 37405 (EWS livery), 37425 (BR Large Logo), 37411 (BR green livery), 37419 (EW&S livery), This loco replaced 37408 "Loch Rannoch" which was involved in a collision with parked stock at Rhymney sidings, which was suspected to be caused by vandals. 37408 suffered from severe extensive damage and was written off at Toton TMD with its power unit removed and used to revive 37422. Its body was later scrapped at European Metal Recycling, Kingsbury, Warwickshire.

By mid 2008, only three Class 37s were still in regular use on the mainline (37401, 417 & 422). 37422 was placed in WNTS tactical store in September leaving only 37401 and 417 in traffic. On 16 December, 37417 failed and was sent to Eastleigh for storage, resulting in 37401 the only Class 37 to remain in traffic into the new DB Schenker era.

The former EWS, DB Schenker Rail (UK) Ltd. had one operational Class 37/4, 37401 at the time of its creation on 1 January 2009. DB Schenker also has hired locomotives for temporary duties, such as 37423 from Direct Rail Services (DRS) to cover for failed 37417. DB Schenker 37401 (and DRS's 37423) were on snowplough duty at Inverness for the winter months. 37401, DB Schenker's sole operational English Electric type 3, was reported sounding rough, and was later stored although this did not last long as it was soon sent to Toton TMD for repairs along with 37406 "The Saltire Society".

37401, DB Schenker's most reliable Class 37, was repaired and is currently back in mainline service. 37406 was returned to service, failing on its first working. 37670 was also returned operational.

37419 was prepared for a return to traffic and saw itself repainted into DB Schenker livery, however its long time in store did not help its power unit and it failed with a serious engine fault on its trial run. The locomotive remains stored.

DB Schenker had the largest route for railhead treatment trains for Autumn 2009 and required Class 37 haulage due to their route availability. Much speculation was surrounding the return of several Class 37s, however DB Schenker were eventually given clearance from Network Rail to use Class 66s and 67s on the routes instead, resulting in the Class 37 plan being ditched despite several of the machines having their air horns moved onto the nose to resolve clearance problems.

Reliability problems plagued 37670 during its short time in traffic and the loco was eventually stored unservicable.

With the storage of 37670, this meant that once again 37401 was the sole operational Class 37 in active service under DB Schenker. To take the load strain off 37401, 37425 "Pride Of The Valleys" was fitted with OTMR safety equipment and was returned fully operational. The locomotive remains in BR blue large logo livery, however like 37670 it is also plagued with unreliability.

As of March 2010, DB Schenker Rail UK ceased using Class 37s.

West Coast Railway Company

The West Coast Railway Company (WCRC) purchased four locomotives from Ian Riley Engineering in 2004. The two operational locomotives (nos. 37197 and 37261) were used on charter trains or as standby locomotives for "The Jacobite" steam-hauled excursion services from Fort William to Mallaig during 2005. These two, along with non-operational 37423, have since been sold to DRS. The fourth (no. 37235) was for spares.

In late 2007, WCRC purchased several non-operational Class 37/5 and Class 37/7s from EWS: nos. 37517, 37668, 37676, 37685, 37706, 37712 and 37710. Of the acquired locomotives 37710 will be used as a source of spares, 37676 and 37712 were the first two returned to mainline. 37676 was named 'Loch Rannoch' at a special event in Carnforth Steamtown. 37712 suffered a fire on an empty coaching stock move and was subsequently stored. It is known that major work will need to be done on 37712, however demand exists for chartered Class 37s.

At the end of 2010, WCRC had four Class 37s running in service: nos. 37516, 37676, 37685 and 37706.

Future

Dilapidated 37079 at Barrow Hill

As of 2011, members of the class are still in mainline service despite some being 50 years old.

Network Rail ERTMS project

Network Rail are currently in the process of restoring four Class 37s as part of the European Rail Traffic Management System (ERTMS) trial project on the Cambrian Line. The site of the restoration is the Barrow Hill Roundhouse, where ex-HNRC locomotives 37100, 37170, 37178 and 37217 have been taken in. The restored Class 37s for ERTMS use have been re-designated as Class 97/3, numbered 97301, 97302, 97303 and 97304.

The class was chosen because of its original fitment with both air and vacuum braking, a feature which will allow it to pull both modern freight trains as well as steam specials. The main work of the locomotives will be to pull on track machines (such as tampers) through the ERTMS section.

The 97/3s are to be based at the newly constructed Coleham Depot for the duration of the ERTMS testing on the Cambrian Line, thereafter they will be used to pilot trains not fitted with the ERTMS signalling system.

These locos are effectively refurbished, having been completely stripped down to bare steel, with reconditioned engines, somewhat updated cabs, all new signalling systems installed (ERTMS in this instance) and extensive re-wiring.

Preservation

Class 37 locomotives have proved to be very popular, with many examples saved for preservation on heritage railways or by enthusiast groups. Notable examples saved include the first-built locomotive, no. D6700, the last built locomotive 37308, Mirrlees-engined prototype no. 37901, and both Ruston-engined prototypes nos. 37905 and 37906. One locomotive, 37372, has been procured by a group called the Baby Deltic Project for conversion into a replica of a Class 23 Baby Deltic.

Pre TOPS	Post TOPS	Final	Name	Owner	Location	Notes or livery
D6605	37305	37407		ST4	Churnet Valley Railway	Out of service. Transrail Grey
D6607	37307	37403	Isle of Mull		Bo'ness and Kinneil Railway	Under restoration. BR Green
D6608	37308	37274			Pullman Rail,Cardiff Canton	BR Blue
D6700	37119	37350		National Railway Museum	National Railway Museum	First locomotive of class built. BR Green
D6703	37003	37003 (37360)		Class 37 Locomotive Group.	Mid-Norfolk Railway	BR Civil Engineers 'Dutch' Carried the nameplates First East Anglian Regiment but these were never unveiled (picture Railway Magazine Sept 1963 p667)
D6709	37009	37340		English electric preservation	Nottingham Transport Heritage Centre	Undergoing restoration. BR Green
D6723	37023	37023		Privately owned	Allely’s yard in Studley	Undergoing restoration. Mainline Blue
D6725	37025	37025	Inverness TMD	The Scottish Thirtyseven Group	Bo'ness & Kinneil Railway	BR Blue Large Logo. Restored in 2005. Currently out of service.
D6729	37029	37029		Privately owned	Epping Ongar Railway	BR Green, small warning panel.
D6732	37032	37353	Mirage	Privately owned / Anglia type three association	North Norfolk Railway	BR Green. Undergoing restoration.
D6737	37037	37321	(Gartcosh)	Devon Diesel Society	North Norfolk Railway	BR Green. Nameplates now removed.
D6742	37042	37042			Eden Valley Railway	"Almost Runnable" EWS Livery
D6775	37075	37075		Privately owned	Churnet Valley Railway	BR Blue
D6776	37076	37518		Privately owned	East Lancashire Railway	Operational. Railfreight red stripe livery.
D6797	37097	37097	Old Fettercairn	Caledonian Railway Diesel Group	Caledonian Railway	Under Overhaul BR Blue
D6799	37099	37324	Clydebridge	Privately owned	Gloucestershire Warwickshire Railway	BR Blue with large numbers. In working order 2000.
D6808	37108	37108		Privately owned	Crewe Heritage Centre	Under restoration. BR Blue
D6809	37109	37109		Bury Diesel Group	East Lancashire Railway	BR Blue
D6816	37116	37116	Sister Dora		Chinnor & Princes Risborough Railway	Trans-Rail livery
D6823	37123	37679		Privately owned	Burton Wagon Works - Nemisis	Currently undergoing long-term restoration. Railfreight 3 Tone Grey: Unspecified Sub-Sector
D6836	37136	37905			Mid Hants Railway	Railfreight livery, Rebuilt with Ruston engine
D6842	37142	37142			Bodmin & Wenford Railway
D6846	37146	37146			Stainmore Railway, Kirkby Stephen	Light restoration, to be run in BR Blue livery
D6850	37150	37901	Mirrlees Pioneer	Privately owned	East Lancashire Railway	Railfreight livery, Rebuilt with Mirrlees engine
D6852	37152	37152		Privately owned	Peak Rail	InterCity Swallow livery, in working order (Sept. 2006)
D6869	37169	37674	St Blaize Church 1445-1995		Stainmore Railway, Kirkby Stephen	Trans-Rail Grey livery. To be restored as D6869 in BR green
D6875	37175	37175	W. S. Sellar (named 2nd July 2011)	Privately owned	Bo'ness and Kinneil Railway	BR Blue Large Logo
D6888	37188	37188		Privately owned	Peak Rail	Undercoat Black
D6890	37190	37314	Dalzell	Class Forty Appeal	Midland Railway Butterley	Large Logo Blue (Eastfield)
D6906	37206	37906			Severn Valley Railway	With Ruston RK270T engine. Railfreight livery
D6907	37207	37207	William Cookworthy		Plym Valley Railway	BR Blue. Under final stages of repairs (2008)
D6915	37215	37215		The Growler Group [2]	Gloucestershire Warwickshire Railway	In working order 1998.
D6916	37216	37216		Private	Pontypool and Blaenavon Railway	Mainline Blue livery. Undergoing restoration to BR Green
D6919	37219	37219	Shirly Ann Smith		Chinnor & Princes Risborough Railway	Mainline livery
D6927	37227	37227			Battlefield Railway	under restoration
D6940	37240	37240		Llangollen Diesel Group	Llangollen Railway	In working order 2010. BR Blue
D6948	37248	37248	(Loch Arkaig)	Privately owned - in custodianship of 'The Growler Group' [3]	Gloucestershire Warwickshire Railway	Under overhaul. WCRC Maroon livery. Nameplates now removed.
D6950	37250	37250
D6954	37254	37254	Driver Robin Prince MBE (named July 2009)	Privately owned, maintenance funded by the '37254 fund'	Spa Valley Railway	Civil Engineers
D6955	37255	37255		Privately owned	Great Central Railway	Civil Engineers.
D6963	37263	37263			Dean Forest Railway
D6964	37264	37264			North Yorkshire Moors Railway	BR Large logo Blue
D6967	37267	37421		Privately owned	Pontypool and Blaenavon Railway	EWS
D6971	37271	37418	Pectinidae	Privately owned	East Lancashire Railway	Out of service.EWS
D6975	37275	37275			Barrow Hill Engine Shed	BR Blue
D6976	37276	37413		Privately owned	Bo'ness and Kinneil Railway	Under restoration EWS
D6979	37279	37424		ST4	Churnet Valley Railway	Out of service. Transrail Grey
Emboldened engine number indicates current number carried by preserved locomotive

Built in 1962, finally withdrawn in 1996, and scrapped in 2004.
Most members of this class were not preserved.

Sources

• Marsden, Colin J. (1981). Motive power recognition:1 Locomotives. Shepperton: Ian Allen Ltd. ISBN 0 7110 1109 5. 
• Preedy, Norman E; Ford, H L. BR Diesels in Close-Up. Truro: D Bradford Barton Ltd. 
• Williams, Alan; Percival, David (1977). British Railways Locomotives and Multiple Units including Preserved Locomotives 1977. Shepperton: Ian Allen Ltd. ISBN 0 7110 0751 9. 

Further reading

• McManus, Michael. Ultimate Allocations, British Railways Locomotives 1948 - 1968. Wirral. Michael McManus. 

External links

• Class 37 Locomotive Group Class 37 - 37003 (37360)
• The Growler Group Class 37 37215, 37248 (custodians)
• English Electric Preservation Class 37 - D6709
• 37 093 in "police" livery at Gateshead TMD