British Rail Class 421

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British Rail Class 421
Unit 1498 4CIG at North Weald 2012.JPG
Class 421/7 no. 1498 at North Weald in 2012. This unit was restored to 1960s-era British Railways green livery for use on the Lymington Branch Line, but has since been transferred to the Epping Ongar Railway. It has also had an extra carriage added to restore its 4Cig formation and is powered by a locomotive at the other end.
In service 1964 - 2010
Manufacturer BREL York
Number built 166 (138 class 421 (4 CIG) and 28 class 422 (4 BIG) Units)
Formation Driving trailer + Motor coach + Trailer/Buffet + Driving trailer
Operator British Rail, South West Trains, Connex South Central, Connex South Eastern, Network South East, Southern, South Eastern Trains
Car length 265 feet 8 12 inches (80.988 m)
Width 9 feet 3 inches (2.82 m)
Height 12 ft 9 14 in (3.893 m)
Maximum speed 90 miles per hour (140 km/h)
Weight 150 long tons (150 t)
Power output 4 x 250 hp traction motors
total 1,000 horsepower (750 kW)
Electric system(s) 750V DC third rail
Track gauge standard gauge
Class 421/3, no. 1717, at Clapham Junction on 20 August 2004. This was one of the final few 'Phase 1' 4Cig units in service with Southern.
Class 421/5, no. 1313, at London Waterloo on 19 July 2003. This is one of 22 "Greyhound" units that were operated by South West Trains. This unit has since been withdrawn and scrapped.

The British Rail Class 421 (or 4Cig) electrical multiple units were built at BR's BREL York Works between 1964 and 1972. Units were built in two batches, and were initially introduced on services on the Brighton Main Line. Later units were introduced on services to Portsmouth. These units replaced older Southern Railway-designed units, such as the 5Bel "Brighton Belle" units, and 4Cor units. Towards the end of their life, with the increasing use of newer trains which were equipped with sliding or plug doors, these trains were known commonly as "slam door trains". The fleet's lifespan was 46 years.

Standard units[edit]

The standard units contained only passenger accommodation, and formed the bulk of the fleet. They were unusual in that all four traction motors were mounted on one non-driving motor coach. Units consisted of two driving trailers, sandwiching the non-driving motor coach and an intermediate trailer.

Units were built in two batches. 'Phase 1' units were built from 1963 to 1966 for the Brighton Line, and were numbered 7301-7336. These were followed in 1970-72 by the 'Phase 2' units, built primarily for the Portsmouth line, numbered 7337-7438.

4Big units[edit]

The 4Big units were similar to the standard units, but contained a buffet car in place of the intermediate trailer.

These units were also built in two batches. 'Phase 1' units were built in 1965/66, and were numbered 7031-48. 'Phase 2' units were built in 1970, and were numbered 7049-7058.

The 4Big fleet were initially classified as Class 420 by British Rail under the new computer numbering system introduced in 1968, and then Class 422.

Vehicle numbering[edit]

The numbering of individual vehicles and details of when units were built are shown in the table below.

Phase Type Unit Nos. Years Built DTCsoL MBSO TSO (*TRSB) DTCsoL
Phase 1 4Cig 7301-7336 1964-65 76076-76111 62017-62052 70695-70730 76022-76057
4Big 7031-7048 1964-65 76112-76129 62053-62070 69301-69318* 76058-76075
Phase 2 4Cig 7337-7366 1970 76581-76610 62287-62316 70967-70996 76611-76640
7367-7437 1970-72 76717-76787 62355-62425 71035-71105 76788-76858
7438 1972 76859 62430 71106 76860
4Big 7049-7058 1970 76561-76570 62277-62286 69330-69339* 76571-76580
Class 421/6 no. 1908 at London Victoria on 15 August 2004. This unit was one of eight modified 'Phase 1' unit fitted with Mk.6 motor bogies. It was also one of only four 'Phase 1' units to be repainted in South Central livery. It was withdrawn in October 2004 and has since been scrapped.


Units were facelifted between 1986 and 1993.

8Mig units[edit]

In 1983 two temporary 8Mig units, numbered 2601-2602, were formed while the 4Big fleet underwent asbestos removal. They were used on the Portsmouth Direct line. Therefore four standard 'Phase 2' 4Cig units, numbers 7401-7404, were reformed with a conventional locomotive-hauled miniature buffet carriage (RMB). Each 8Mig unit was formed by marshalling the RMB coach in between two units, one of which was reduced to three carriages, with the removal of the intermediate trailer (TSO). Thus in effect each 8Mig unit was effectively formed of 4Cig + RMB + 3Cig. The formations of the units are listed below:

8Mig unit No. 4Cig unit RMB coach 3Cig unit
Unit no. DTCsoL MBSO TSO DTCsoL Unit no. DTCsoL MBSO DTCsoL
2601 7401 76751 62389 71069 76822 1872 7402 76752 62390 76823
2602 7403 76753 62391 71071 76804 1873 7404 76754 62392 76825

These units were only used during the summer of 1983, after which enough asbestos-free 4Big units were available. The two 8Mig units were disbanded and the four 4Cig unit reformed. The 4Cig units have since been renumbered several times, as shown below:

Unrefurbished Facelifted
74xx series 12xx series 18xx series 8Dig unit 18xx series
7401 1201 1868 - -
7402 1202 1860 - -
7403 1203 1869 - -
7404 1204 1875 2001 1802
Class 421/7, no. 1410, at Clapham Junction on 19 July 2003. This unit was one of eleven 3Cop units converted from redundant 4Big units in 1997, for use on Brighton Coastway services by Connex South Central. Since then, this unit has been augmented to a 4Cop with the addition of a 'Phase 1' intermediate trailer. It was one of the final three such units in service and was withdrawn in March 2005.

8Dig units[edit]

In 1992 four 8Dig units, numbered 2001-2004, were formed by semi-permanently coupling a 4Cig and a 4Big unit. The units were dedicated to London Victoria to Brighton express services, which were operated as the Capital–Coast Express.

The 8Dig units were formed from four 'Phase 2' 4Big units plus two 'Phase 1' and two 'Phase 2' 4Cig units. The 'Phase 1' units, numbers 1901/02 (recently renumbered from 1715/16), were fitted with Mk.6 motor bogies. Interestingly one of the 'Phase 2' 4Cig units, no. 1875 (ex. 7404), had previously been part of 8Mig unit 2602. Unit formations are listed below:

8Dig unit no. 4Cig unit 4Big unit
2001 1875 76754 62417 71072 76850 2262 76779 62392 69333 76825
2002 1902 76100 62041 71768 76046 2254 76732 62379 69306 76803
2003 1801 76777 62415 71095 76848 2255 76740 62378 69310 76811
2004 1901 76082 62023 70701 76028 2259 76748 62386 69318 76819

The units were disbanded in 1996, after replacement by dedicated Class 319/2 units. The various 4Cig and 4Big units were reformed and gained their original numbers, except unit 1875, which was renumbered to 1802.

Class 421/4, no. 1879, at Charing Cross on 18 March 2003, with a service to Hastings. This unit was operated by South Eastern Trains, and is painted in Network SouthEast livery. This unit has since been withdrawn from traffic and scrapped.

Final years of operation[edit]

Two units had remained in service until 22 May 2010, 3Cig units nos. 1497 and 1498, which were used on the Lymington Branch Line. These two units were withdrawn from service on 22 May 2010 and replaced by Class 158 Diesel Multiple Units. 1497 is now preserved at The Mid Norfolk Railway and 1498 is now preserved on the Epping Ongar Railway.[1] The latter has had an extra carriage added to restore its original 4Cig formation.

Privatisation to withdrawal[edit]

After rail privatisation in the mid-1990s the different divisions of British Rail were divided up into different franchises. The three former SR division – South-Eastern, South Central and South-Western – all operated 4Cig units, and are dealt with separately here.

South Eastern Trains[edit]

South Eastern Trains (SET) operated a small fleet of three 'Phase 1' and 22 'Phase 2' 4Cig units. The franchise was originally operated by Connex as Connex South Eastern.

All but one of the 'Phase 2' units continued to carry the obsolete Network SouthEast livery. One unit, no. 1870, was repainted into Connex yellow and white. The three 'Phase 1' units were painted in white undercoat livery, since their use was originally only supposed to be short-term. However, despite this, the units remained in traffic for seven more years, from 1997 to 2004. They were popularly known as "Ghosts" by rail enthusiasts.

From 2003 units started to be withdrawn, having been replaced by the second batch of the new "Electrostar" units. The three 'Phase 1' units had gone by mid-2004. The final unit, no. 1843, lingered on for several months longer than its classmates, eventually being withdrawn in mid-November 2004. All the SET units have been scrapped.

Class 421/4, no. 1861, at Clapham Junction on 19 July 2003, on the rear of a service to Brighton. This unit was one of a handful repainted into the new South Central livery.

South Central / Southern[edit]

The South Central Division inherited the largest fleet of 4Cig units. Originally this included all remaining 'Phase 1' units (though some were later transferred to South Eastern Trains), 35 'Phase 2' units, and the four 8Dig units. The remaining few 4Big units were also used on the former Central Division.

The South Central franchise was initially won by Connex South Central, which applied its yellow and white livery to most stock. In 2000 it lost the franchise to the Go-Ahead Group, which operated the franchise as South Central. In 2004 this was changed to Southern. Four 'Phase 1' units (nos. 1735/38/40, 1908) and eight 'Phase 2' units (nos. 1854/56-62) received Southern's new green livery.

In 1997 the remaining 4Big units were withdrawn. Eight were transferred to South West Trains. The remaining eleven unit were heavily rebuilt at Eastleigh Works, with compartments removed and opened out, and the buffet carriages withdrawn. The modified units were reclassified as Class 421/7 and renumbered into the 1401–1411 range. The units were also known as 3Cop units, which denoted their intended use, i.e. dedicated to East Coastway and West Coastway services out of Brighton. Two units received names – a rarity for slam-door EMU stock.

In 2004 some units were augmented to four carriages with the addition of a 'Phase 1' intermediate trailer, and thus became 4Cop units.

From 2003 Southern started to replace its slam-door fleet with new Class 377 Electrostar units. In general the 'Phase 1' units were withdrawn first due to their age, but as deliveries of the Electrostars increased some 'Phase 2' units were also taken out of service. By late 2004 only a handful of 'Phase 1' units and 4Cops remained in service. The final 'Phase 1' units in traffic were nos. 1704/08/11/12/14/17/43 and 1901, with the final unit, no. 1704, being withdrawn in February 2005. The final 4Cop units, nos. 1404/10/11, were withdrawn in March 2005.

The 'Phase 2' units lasted longer and two, nos. 1805 and 1866, were retained beyond August 2005, when slam-door trains lost all diagrammed work. They lasted until 19 November 2005, when they worked a farewell railtour, following which they were withdrawn.

Class 421/8, no. 1396, at Clapham Junction on 19 July 2003. This unit is one of eight "Greyhound" units converted from redundant 4Big units for use by South West Trains. The buffet coach was replaced with a spare 4Cep trailer vehicle, which is identifiable by its different windows as the second vehicle in the unit.

South West Trains[edit]

4Cig in 1980 in Guildford.

South West Trains inherited a small fleet of twelve 'Phase 2' 4Cig units, and the larger fleet of 22 "Greyhound" units which had been modified to cut several minutes from journey times on the Portsmouth Direct line with its 1 in 80 gradients by adding a second stage of field weakening to improve performance at higher speeds (17% at 54 mph, 30% at 90 mph).

In 1997 the fleet was augmented with the addition of eight 4Big units from Connex South Central. These operated with the counter in the buffet carriages locked out of use. By 1999 these units had been stored, but then eight additional "Greyhound" units were converted from the redundant 4Bigs. The units were reclassified as Class 421/8, and renumbered in the range 1392–1399. The modifications included the removal of the buffet carriages, which were replaced by spare intermediate trailers from mechanically similar 4Cep units. Most of these trailers came from 4Cep units to make 3Cep units, but a few came from withdrawn units. These trailers were immediately recognisable since although they had the same body profile as the rest of the unit the windows were different and they had InterCity70 seating. The buffet carriages were withdrawn, although many were saved for preservation.

The last day of operation on the Lymington Branch Line

In December 2004 unit no. 1394 was reduced to a three-car unit with the removal of its Cep trailer. It was reclassified as Class 421/7, renumbered 1499, and dedicated to the Lymington Branch Line service, where it replaced the previous incumbent unit, no. 1198.

Withdrawals of units started in mid-2004, when many new Class 444 and Class 450 "Desiro" units became available for service. By the end of 2004 just a handful of units remained in traffic. The final few units were withdrawn in May 2005, with the last in traffic being 1304/09/12/16, 1392/95/96/97/98, 1499 and 1881/90. The final slam-door service ran on 26 May from London Waterloo to Bournemouth using units 1396, 1398 and 4Vep 3536. Following withdrawal two units, nos. 1304 and 1881, were transferred to "warm storage" for use by Southern if required. Most of the other units were sent for scrap, with the exception of nos. 1392 and 1499.

Services on the Lymington Branch Line were operated as a "heritage" operation using one of two refurbished 3Cig units, nos. 1497 and 1498. The two units were launched into service on 12 May 2005 having been repainted into heritage liveries, 1497 in blue and grey and 1498 in the green that the units carried when built. However, in May 2010, the new timetable changes saw the units replaced for more modern stock to save maintenance on a non-standard fleet of two units. As stated in the relevant timetable, "The slam door trains will be remembered with affection as they pass into history." The change took place on 22 May 2010 and the units have been replaced by a Class 158 on weekdays and a Class 450 Desiro at weekends. The class 421s have both been preserved due to historic significance.

Accidents and incidents[edit]

Main article: Purley rail crash
  • On 4 March 1989, unit No. 1280 was one of two that formed a passenger train that overran a signal and collided with another passenger train at Purley, Surrey. Five people were killed, 8 were injured.[2]

Further use[edit]

Following withdrawal from normal service several vehicles have seen further use in departmental service.

  • 3Cop unit 1401 was employed as depot shunter at Ashford Chart Leacon depot. However, it was made redundant when Chart Leacon stopped overhauls of slam-door stock and was sent for scrap in July 2005.
  • MBS 62356 (ex-unit 1850) was converted into an ultrasonic test train vehicle for use by Network Rail. It has been renumbered 999606.
  • The rest of unit 1850, namely DTC 76629, TS 71036 and DTC 76789, were retained by Network Rail to provide spares for 999606 but have now been scrapped by C.F. Booth in Rotherham.
  • One vehicle, no. 76112 from 'Phase 1' 4Cig unit 1749, was rebuilt as the Class 424 "Networker Classic" prototype in 1997. It was displayed to the public at London Victoria, paired with unrebuilt driving trailer 76747 from 4Big unit 2256, for comparison purposes. The project was shelved and the vehicle was scrapped in early 2012.
  • DTCSoL vehicles 76765 and 76836 (from 1882) plus 76775 and 76846 (from 1890) were released recently by HSBC from Shoeburyness for parts stripping at Derby RTC, after which they went to C.F. Booth.


So far seven units have been preserved. In addition numerous buffet cars from 4Big units have also been preserved. The full list is shown below, with complete units highlighted:

  • 'Phase 1' unit 1753 has been preserved by the Network SouthEast Railway Society and is stored at Ellough Airfield, near Beccles, Suffolk. This is a private location, visits by arrangement only.
  • 'Phase 2' unit 1881 was purchased by Knights Rail Services Ltd and moved from MOD Shoeburyness to Eastleigh Works in June 2007 along with "Greyhound" unit 1304 and a hybrid Cig/Vep unit comprising vehicles from units 1884 and 3536. Unit 1881 was intended for heritage/excursion traffic on the main line. The unit was successfully powered up at the Works in October 2008, becoming the first preserved EMU to draw third rail power in recent times. The unit was sold to a group of preservationists working on restoring a Brighton Belle train and unit 1881 has had all usable components removed at Barrow Hill and awaits scrapping.
  • 'Phase 2' "Greyhound" unit 1399, also a former 4Big unit, was preserved on the Dartmoor Railway. It was rescued from there by 'Save the Cigs' (see ) and three vehicles were transferred in June 2008 to a secure home on the Pontypool and Blaenavon Railway. (One of this unit's driving trailers, 76747, was displayed along with the prototype "Networker Classic" coach to provide an opportunity for comparison.) Since then 76818 has been undergoing major works at Eastleigh, while the other DTC and TSO were to feature in the film 'Lost Passenger' before returning to Dartmoor Railway
  • 4Cig unit 1392 and 3Cig unit 1499 were preserved at the Dean Forest Railway. The latter was previously dedicated to services on the Lymington Branch Line. Both are no longer in existence following vandalism. CEP TSO from 1393 was moved to Dartmoor Railway.
  • It was hoped that unit 1705 (formerly 7301), the first-built unit, would be preserved by Southern, for use on special excursion trains. Unfortunately its poor condition precluded this and it was eventually scrapped.
  • South West Trains has retained two 'Phase 2' 3Cig units after their withdrawal and replacement on the Lymington branch.
  • 14 February 2008. TSO vehicle 71085 from 1884 was delivered from store at Shoeburyness to Deptford, where it has become a café.
  • 3Cig unit 1497 is preserved on the Mid-Norfolk Railway, arriving on 28 September 2010. The unit was delivered by rail, coupled to 73201 and driven to Dereham in push-pull mode. It is planned to receive a BIG buffet car, making it the only 4BIG in existence.

Preserved units[edit]

Unit Number
(current in bold)
Type Phase DTCsoL MBSO TSO
DTCsoL Livery Location Notes
7032 2101 2251 - - 4Big Phase 1 - - 69302* - Network SouthEast Abbey View Disabled Centre -
7034 2110 2260 - - 4Big Phase 1 - - 69304* - Network SouthEast Northamptonshire Ironstone Railway Trust -
7036 2104 2254 2002 - 4Big Phase 1 - - 69306* - BR(S) Green Spa Valley Railway - Used as a static cafe as Tunbridge Wells West station.
7040 2105 2255 2003 - 4Big Phase 1 - - 69310* - BR(S) Green Dartmoor Railway -
7046 2108 2258 - - 4Big Phase 1 - - 69316* - BR(S) Green Riccarton Junction Waverley Route heritage centre.
7048 2109 2259 2004 - 4Big Phase 1 - - 69318* - BR(S) Green Mid Norfolk Railway -
7051 2203 - - - 4Big Phase 2 - - 69332* - Network SouthEast Dartmoor Railway -
7053 2205 - - - 4Big Phase 2 - - 69339* - BR(S) Green Finmere
7055 2207 2112 2262 2001 4Big Phase 2 - - 69333* - BR(S) Green Lavender Line -
7057 2209 - - - 4Big Phase 2 - - 69335* - LNER Green/Cream Wensleydale Railway -
7058 2210 - - - 4Big Phase 2 - - 69337* - BR Green Hastings Diesels Operates with preserved Class 201 unit 1001.
7327 1127 1753 - - 4Cig Phase 1 76102 62043 70721 76048 Connex Network SouthEast Railway Society -
7373 - 1819 1306 - 4Cig Phase 2 - - 71041 - Green Hever railway station In use as office extension by station building owners.
7376 1276 2251 1394 1499 4Cig Phase 2 - 62364 - - South West Trains Derby 76726, 71080, 76797 sold for scrap. 62364 to RVEL Derby. Conversion to UTU coach.
7397 1297 2256 1399 - 3Cig Phase 2 76747 62385 70508 76818 BR Green 76747, 62385 & 70508 at Dartmoor Railway 9/11/11. 76818 at Eastleigh Works. 76747 into BR Green 10/05/12. Last surviving SWT "Greyhound" unit.
7414 1214 1883 1497 - 3Cig Phase 2 76764 62402 #69318 76835 BR Blue/Grey Mid-Norfolk Railway PRIVATELY PURCHASED for use on the Mid Norfolk Railway. #TRBS is planned to be added to unit upon completion of restoration.
7417 1217 1884 - - 4Cig Phase 2 - - 71085 - White / Art Design Morden Wharf, Greenwich Now out of use, in store.
7423 1223 1888 1498 - 3Cig Phase 2 76773 62411 - 76844 BR Green Epping Ongar Railway Formerly on the Lymington Branch Line. In use on the Epping Ongar Railway until mid 2013.
Unit surplus to requirements, now for sale.

Fleet details[edit]

Original-condition Units

Class Type No. built


Year built


No. range Withdrawn Notes
Class 420 4Big 18 1965-66 7031-7048 1986 Facelifted 1985-86, and renumbered as Class 422 units 2101-2112.
10 1970 7049-7058 1988 Facelifted 1986-88, and renumbered as Class 422 units 2201-2210.
Class 421 4Cig 36 1963-66 7301-7336

(later 1101-1136)

1993 Facelifted 1986-1993, and renumbered into 17xx range.
102 1970-74 7337-7438

(later 1201-1300)

1993 Facelifted 1987-1993, and renumbered into 18xx and 13xx range.
Class 421 8Mig 2* 1983* 2601–2602 1983 Converted back to standard 4Cig.

Facelifted units

Class Type No.




No. range Operator Units nos. Withdrawn No. preserved
Class 421/3 4Cig 53 1986-93 1701–1753 SET 1701/42/48 06/2004 1
Southern 1702-14/17/19-22/24-27/31/33-48/50-53 02/2005
Class 421/4 4Cig 87 1987-93 1801–1826


SET 1806-1813/39-43/70-73/75-79 11/2004 -
Southern 1801-1805/31-35/37/45-48/50/51/53-69/74 11/2005
SWT 1880-1891 05/2005
Class 421/5 4Cig 22 1990-92 1301–1322 SWT 1301-1322 05/2005 -
Class 421/6 4Cig 8 1994 1901–1908 Southern 1901-1908 01/2005 -
Class 421/7 3Cop 11 1997 1401–1411 Southern 1401-1411 03/2005 -
3Cig 3 2004-05 1497–1499 SWT 1497-1499 05/2010 2
Class 421/8 4Cig 8 1999 1392–1399 SWT 1392-1399 05/2005 1
Class 422/0 8Dig 4 1992 2001–2004 South Central 2001-2004 1996 -
Class 422/1 4Big 10 1985-86 2101–2112 BR 2101-2112 1989 -
Class 422/2 4Big 10 1986-88 2201–2210 South Central 2203-06/8-10 1997 -
Class 422/3 4Big 12 1989 2251–2262 South Central 2251-62 1997 -
SWT 2251/54-56/58/59/61/62 1999


Class 421 South West Trains Diagram.PNG
Class 421 South West Trains Rail Blue Diagram.PNG


  1. ^ Jones, Robin (2010). "End of line for Lymington slam-door stock". Heritage Railway (134 (18 February - 17 March 2010)): p61. 
  2. ^ Vaughan, Adrian (2003) [2000]. Tracks to Disaster. Hersham: Ian Allan. p. 89. ISBN 0 7110 2985 7.