The Southern Railway created classification and numbering systems for its large fleet of electric multiple unit

Electric multiple unit

An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...

s that were perpetuated by the Southern Region of British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

 until the early 1980s, when the impact of TOPS

TOPS

Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...

 was felt. Even now, some stock have still been allocated Southern-style classifications in a semi-official manner.

Classification

The early AC overhead electric multiple unit types were referred to by a two-letter code. This was adapted for the DC third-rail system that was adopted as standard by the Southern Railway, with unit type being given a three-letter code (sometimes two letters) prefixed by the number of carriages within each unit, e.g. 4SUB for a 4-car suburban set.

The Southern Region of British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

 perpetuated this method of classification, and the same principles were also adopted for diesel-electric multiple unit stock, but with single-letter codes. The last type to be officially allocated a designation in this series was the PEP stock of the early 1970s. However, some types built since then have been given semi-official designations in this style.

NB: This was different from the system used by British Rail (adopted from the LNER) to indicate the type of non-powered coach — see British Rail coach designations

British Rail coach designations

The London, Midland and Scottish Railway and the London and North Eastern Railway both developed a system of identifying railway carriages by means of alphabetic codes...

.

AC overhead EMUs

SR Designation	Meaning
CP SR Class CP The Southern Railway gave the designation CP to the fleet of AC electric multiple units used on the former London, Brighton and South Coast Railway lines in the Crystal Palace area.-Construction:...	Crystal Palace Stock
CW SR Class CW The Southern Railway gave the designation CW to the fleet of AC electric multiple units used on the lines to Coulsdon and Wallington. They were planned by the London, Brighton and South Coast Railway but were delayed by the World War I and the grouping and were introduced by the Southern...	Coulsdon & Wallington Stock
SL SR Class SL The Southern Railway gave the designation SL to the fleet of AC overhead electric multiple units used on the South London Line. These had been built by the London, Brighton and South Coast Railway in 1909, but with the abandonment of the Elevated Electric service in 1928 they were converted to DC...	South London Stock

DC third rail EMUs

SR Designation	BR Class	Meaning
GLV	489 British Rail Class 489 The British Rail Class 489 is a type of electrical multiple unit, specially converted for use on Gatwick Express trains, from London Victoria to Gatwick Airport....	Gatwick Luggage Van
MLV	419 British Rail Class 419 The British Rail Class 419 Motor Luggage Vans were built from 1951-61 by BR at Eastleigh Works.-Description:Ten of these units were built for the boat trains from London Victoria to Dover and Folkestone...	Motor Luggage Van
TLV	499 British Rail Class 499 British Rail allocated Class 499 to a fleet of six luggage vans used in electric multiple unit formations on boat train services between London and Dover. They were allocated Southern Region class TLV ....	Trailer Luggage Van
2BIL	401 British Rail Class 401 The Southern Railway gave the designation 2-BIL to the DC third rail electric multiple units built during the 1930s to work long-distance semi-fast services on the newly electrified lines from London to Eastbourne, Portsmouth and Reading...	Bi-Lavatory Stock
2EPB	416 British Rail Class 416 British Rail Class 416 electric multiple units were built between 1953 and 1956. They were intended for inner suburban passenger services on London's Southern Electric network...	Electro-Pneumatic Brake Stock
2HAL	402 British Rail Class 402 The Southern Railway gave the designation 2-HAL to the electric multiple units built during the late 1930s to work long-distance semi-fast services on the newly electrified lines from London to Maidstone and Gillingham...	Half Lavatory Stock
2HAP	414 British Rail Class 414 The British Rail Class 414 electric multiple units were built between 1956 and 1963.209 of these two car units were built to two similar sub-classes. The first batch of thirty-six units were built on the underframes of older SR Class 2Nol units, and numbered in the range 5601-5636...	Half lavatory with electro-Pneumatic Brake Stock
2NOL SR Class 2Nol The Southern Railway gave the designation 2-NOL to the electric multiple units built during the 1930s from old London and South Western Railway carriage bodies on new underframes...	-	No Lavatory Stock
2PAN	402	Parcels and Newspapers Stock
2PEP	446 British Rail Class 445 The PEP Stock were prototype electric multiple units used on British Rail's Southern Region during the early 1970s. They were forerunners of the BR Second Generation electric multiple unit fleet. Three units were built, one two-car unit , and two four-car units...	Prototype Electro-Pneumatic Brake Stock
2SAP	418 British Rail Class 414 The British Rail Class 414 electric multiple units were built between 1956 and 1963.209 of these two car units were built to two similar sub-classes. The first batch of thirty-six units were built on the underframes of older SR Class 2Nol units, and numbered in the range 5601-5636...	Second-Class Only Hap Stock
2SL SR Class 2SL The Southern Railway gave the designation 2-SL to the small fleet of electric multiple units dedicated for use on the South London lines. None of these units survived long enough in British Rail ownership to be allocated a TOPS class.-Construction:...	-	South London Stock
2WIM SR Class 2Wim 2-WIM was the designation given, by Southern Railway , to a small fleet of electric multiple units, dedicated for use on the West Croydon to Wimbledon Line...	-	Wimbledon Line Stock
3COP	421 British Rail Class 421 The British Rail Class 421 electrical multiple units were built at BR 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...	Coastway Open Plan
3SUB British Rail Class 405 Under the British Rail TOPS computer system, Class 415 was allocated to surviving examples of the Southern Railway 4-Sub Class electric multiple units built between 1941 and 1951...	-	Suburban Stock
3TC	492 British Rail Class 438 The British Rail TC multiple units were un-powered fixed formations of 3 or 4 carriages with a driving position at each end of the set, converted by BR at York Works from locomotive-hauled Mark 1 carriages in 1966-1967 and 1974. The units built on experience gained from the prototype 6TC unit...	Trailer Control Stock
3TIS	486	Vectis (Isle of Wight) Stock
4BEP	412	Buffet Electro-Pneumatic Brake Stock
4BIG	422	Buffet Brighton Stock
4BUF	404 British Rail Class 404 The Southern Railway gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour. The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404...	Buffet Stock
4CAP	413 British Rail Class 413 The British Rail Class 413 units were formed in 1982 by permanently coupling two Class 414 2Hap units together. The cabs in the centre of the unit were decommissioned, thus reducing the weight of the units....	Coastway Hap Stock
4CEP	411 British Rail Class 411 The British Rail Class 411 electrical multiple units were built at Eastleigh works from 1956-63 for the newly electrified main lines in Kent. These units were based on the earlier Southern Railway 4Cor design, built in 1937. They were replaced by Juniper units.-Description:A total of 133 units...	Corridor Electro-Pneumatic Brake Stock
4CIG	421 British Rail Class 421 The British Rail Class 421 electrical multiple units were built at BR 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...	Corridor Brighton Stock
4COR	404 British Rail Class 404 The Southern Railway gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour. The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404...	Corridor Stock
4DES	450 British Rail Class 450 The British Rail Class 450 third-rail DC EMU began service during 2003. They are a part of the Siemens Desiro modular train family and are more commonly known as the 'Blue Desiro'...	Desiro
4DD	-	Double Decker Stock
4EPB	415 British Rail Class 415 British Rail Class 415 was a suburban 750 V DC third rail electric multiple unit commissioned by the Southern Region of British Railways. Built between 1951 and 1957, it became the most numerous class on the region after the withdrawal of the 4Subs...	Electro-Pneumatic Brake Stock
4GRI	404 British Rail Class 404 The Southern Railway gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour. The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404...	Griddle Car Stock
4JOP	458 British Rail Class 458 The South West Trains Class 458 electrical multiple units were built by Alstom at Washwood Heath between 1998 and 2002. These units are part of Alstom's Juniper family of units, which also includes Classes 334 and 460.-Description:...	Juniper Outersuburban Porterbrook
4LAV SR Class 4Lav The Southern Railway gave the designation 4-LAV to the electric multiple units built to work the semi-fast services on the route between London and Brighton...	-	Lavatory Stock
4PEP	445 British Rail Class 445 The PEP Stock were prototype electric multiple units used on British Rail's Southern Region during the early 1970s. They were forerunners of the BR Second Generation electric multiple unit fleet. Three units were built, one two-car unit , and two four-car units...	Prototype Electro-Pneumatic Brake Stock
4REP	432 British Rail Class 432 The British Rail 4-REP electric multiple units were built by BR at York Works from 1966-1967 and 1974. The units were built to power the 4-TC trailer units on services on the South Western Main Line. Fifteen four-car units were eventually built. The motor coaches were new build, but the trailers...	Restaurant Electro-Pneumatic Brake Stock
4RES	404 British Rail Class 404 The Southern Railway gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour. The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404...	Restaurant Stock
4SUB	405 British Rail Class 405 Under the British Rail TOPS computer system, Class 415 was allocated to surviving examples of the Southern Railway 4-Sub Class electric multiple units built between 1941 and 1951...	Suburban Stock
4TC	438 British Rail Class 438 The British Rail TC multiple units were un-powered fixed formations of 3 or 4 carriages with a driving position at each end of the set, converted by BR at York Works from locomotive-hauled Mark 1 carriages in 1966-1967 and 1974. The units built on experience gained from the prototype 6TC unit...	Trailer Control Stock
4TEP	412	Temporary BEP Stock
4VEC	485 British Rail Class 485 The British Rail Class 485 and British Rail Class 486 electrical multiple units were original built for the London Electric Railway from 1923-31 as their 'Standard' tube stock...	Vectis (Isle of Wight) Stock
4VEG	427	VEP Gatwick Express Stock
4VEP	423 British Rail Class 423 The British Rail Class 423 electrical multiple units were built by BR at York Works from 1967 to 1974, although the MBSOs and TSOs of the first 20, 7701-7720, were constructed at Derby Works. They feature manually-opening doors next to every seating row and were the last coaching stock built in...	Vestibule Electro-Pneumatic Brake Stock
4VIP	423 British Rail Class 423 The British Rail Class 423 electrical multiple units were built by BR at York Works from 1967 to 1974, although the MBSOs and TSOs of the first 20, 7701-7720, were constructed at Derby Works. They feature manually-opening doors next to every seating row and were the last coaching stock built in...	VEP Intermediate Plan
4VOP	423 British Rail Class 423 The British Rail Class 423 electrical multiple units were built by BR at York Works from 1967 to 1974, although the MBSOs and TSOs of the first 20, 7701-7720, were constructed at Derby Works. They feature manually-opening doors next to every seating row and were the last coaching stock built in...	VEP Open-Plan
5BEL	403 British Rail Class 403 The Southern Railway gave the designation 5BEL to the 5-car all-Pullman electric multiple units which worked the prestigious Brighton Belle trains between London Victoria and Brighton. These units survived long enough in British Rail ownership to be allocated TOPS Class 403...	Brighton Belle Pullman Stock
5DES	444 British Rail Class 444 The British Rail Class 444 Desiro electrical multiple units were built in Germany by Siemens AG from 2003-04. Forty-five of these units were built for express services for South West Trains....	Desiro
5TCB	438 British Rail Class 438 The British Rail TC multiple units were un-powered fixed formations of 3 or 4 carriages with a driving position at each end of the set, converted by BR at York Works from locomotive-hauled Mark 1 carriages in 1966-1967 and 1974. The units built on experience gained from the prototype 6TC unit...	TC and Buffet Stock
5WES	442 British Rail Class 442 The British Rail Class 442 Wessex Electric electrical multiple units were introduced in 1988 on the South Western Main Line from London Waterloo to Southampton Central, Bournemouth, Poole and Weymouth. Twenty-four of these 5-car units were built in 1988/89 by BREL at its Derby works...	Wessex Stock
6CIT SR Class 6Pul The Southern Railway gave the designations 6-PUL, 6-CITY and 6-PAN to electric multiple units built to work the routes between London and Brighton, West Worthing and Eastbourne. None of these units survived long enough in British Rail ownership to be allocated a TOPS class number...	-	City Limited Stock
6PAN SR Class 6Pul The Southern Railway gave the designations 6-PUL, 6-CITY and 6-PAN to electric multiple units built to work the routes between London and Brighton, West Worthing and Eastbourne. None of these units survived long enough in British Rail ownership to be allocated a TOPS class number...	-	Pantry Stock
6PUL SR Class 6Pul The Southern Railway gave the designations 6-PUL, 6-CITY and 6-PAN to electric multiple units built to work the routes between London and Brighton, West Worthing and Eastbourne. None of these units survived long enough in British Rail ownership to be allocated a TOPS class number...	-	Pullman Stock
6REP	431 British Rail Class 432 The British Rail 4-REP electric multiple units were built by BR at York Works from 1966-1967 and 1974. The units were built to power the 4-TC trailer units on services on the South Western Main Line. Fifteen four-car units were eventually built. The motor coaches were new build, but the trailers...	Reformed REP Stock
6TC	-	Trailer Control Stock
6JAV	395 British Rail Class 395 British Rail Class 395 is a dual-voltage electric multiple unit used by train operating company Southeastern for its services along High Speed 1 and onwards to the Kent coast. The trains were built in Japan by Hitachi and shipped to the United Kingdom to operate new high speed domestic services...	JAVlin Stock. Unofficial Classification, also referred to as 6HIT (Hitachi).
7TC	-	Trailer Control Stock
8DIG	422	Dedicated Brighton Stock
8GAT	460 British Rail Class 460 The British Rail Class 460 electrical multiple units were built by Alstom at Washwood Heath from 2000-01. These units are part of Alstom's "Juniper" family of units, which also includes Classes 334 and 458...	Gatwick Express Stock
8MIG	421	Miniature Buffet and CIG Stock
8VAB	480	Vestibule Autobrake Buffet Stock

Diesel-electric multiple units

SR Designation	BR Class	Meaning
3D	207 British Rail Class 207 The British Rail Class 207 diesel-electric multiple units were built by BR at Eastleigh in 1962.-Technical details:Power car * Introduced: 1962* Weight: 56 tons...	Oxted Line Stock
3H	205 British Rail Class 205 The British Rail Class 205 diesel-electric multiple units were built by BR at Eastleigh from 1957–1962. They were replaced by Turbostar units.-Description:This class of unit were built in four different batches for use on different lines....	Hampshire Stock
3R	206 British Rail Class 206 The British Rail Class 206 or 3R was a type of Diesel electric multiple unit first created in 1964. They were not 'built' as such but rather re-formed from Class 201 and EPB vehicles for use on -- services...	Reading Line Stock
3T	204 British Rail Class 204 The British Rail Class 204 designation has been used twice for two similar types of diesel-electric multiple units.The original units, numbered in the range 1119-1122, were two-car versions of the Class 205 '3H' units, and were classified as 2H under the old system.In 1979, BR decided to augment...	Hampshire and added Trailer Stock
6B	203 British Rail Class 203 The British Rail Class 203, initially classified 6B, was a type of diesel electric train. Seven units, numbered 1031-1037, were constructed in 1958 for use on the Southern Region...	Hastings Buffet Stock
6L	202 British Rail Class 202 The British Rail Class 202 diesel-electric multiple units were built from 1957-58 at Eastleigh and Ashford Works. These units were built to work the London Charing Cross to Hastings services...	Hastings Long-frame Stock
6S	201 British Rail Class 201 The British Rail Class 201 six-car diesel-electric multiple units were built in 1957-1958 at Eastleigh and Ashford. They were built for use on the London-Hastings line...	Hastings Short-frame Stock

Unit numbering

Unit numbers were allocated in a series commencing from 1001, which followed the set numbers given to semi-fixed formations of hauled coaching stock, 1-1000. Different types of unit were given numbers according to the following division:

1001–1200	Unpowered trailer units for working with 3SUB stock (this series was later expanded to include unit numbers 989-1000)
1201-1800	3SUB stock (ex-LSWR units had 1200 added to their original number)
1801–1999	Two-car inner-suburban stock (e.g. 2NOL)
2001-2899	Two-car outer-suburban stock (e.g. 2BIL)
2901-3999	Four-, five- and six-car outer-suburban stock (e.g. 4LAV)
4001-4999	Four-car inner-suburban stock (4SUB and 4DD)
5001-5599	British Railways four-car inner-suburban stock (4EPB)
5601-6999	British Railways two-car stock (e.g. 2HAP)
7001-7999	British Railways four-car outer-suburban stock (e.g. 4CIG)
8001	Temporary eight-car formation (8VAB)
S1-S101	Departmental (non-revenue earning) stock

This series was perpetuated by the Southern Region of BR, though with modifications, as older set numbers were reused for the following different types:

001-099	Parcels and departmental stock (Former Sxxx units renumbered into this series)
301-999	Trailer Control stock (first digit indicated number of cars, e.g. 301 = 3TC)
1001-1499	Diesel Electric Multiple Units (e.g. 6S)

The 2PEP stock reused number 2001, the 4REP stock reused numbers from 3001 and the 4PEP stock reused numbers 4001/4002. This series was abandoned only in 1983, when units were renumbered to fit in with the TOPS classification system, which had nominally been in use for a decade. Even then, many units only displayed the last four digits of their TOPS number, dropping the first two digits - e.g. unit 412 301 would have the number "2301" applied. Only with later units and the 2xx series DEMUs were the full numbers shown, e.g. Classes 456

British Rail Class 456

The British Rail Class 456 electric multiple-unit trains were built by BREL at York Works from 1990-91.- Description :24 two-car units were built as direct replacements for the elderly Class 416 2EPB units which operated on the Central Division of the Southern Region of British Rail. Units were...

, 465

British Rail Class 465

The British Rail Class 465 Networker electric multiple units were built by GEC Alsthom and BREL between 1991 and 1993, and by ABB Rail between 1993 and 1994. They were brought into service from 1991 onwards. They are mostly used on suburban routes serving the South East of England, now operated by...

 and 466

British Rail Class 466

The Class 466 750 V DC third rail electric multiple unit is a suburban EMU, which operates with Class 465 EMUs in southeast London and Kent on the Southeastern network...

, along with some Class 455

British Rail Class 455

The British Rail Class 455 is a type of electric multiple unit drawing power from a 750 V DC third rail. Built by BREL at York works in the early and mid-1980s, they were initially categorised as Class 510 as the successor to the Class 508...

sets, carry full 6-digit numbers.