British Rail Class 421

Standard fleet

These 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. Trains consisted of two driving trailers, sandwiching the non-driving motor coach and an intermediate trailer.

Trains were built in two batches: 'Phase 1' units were built from 1963 to 1966 for the Brighton Line and were numbered 7301-36; these were followed in 1970-72 by the 'Phase 2' units, built primarily for the Portsmouth Direct line, numbered 7337-438.

4-BIG fleet

The 4-BIGs were similar to the class standard, but contained a buffet car in place of the intermediate trailer. They were also built in two batches: 'Phase 1' trains were built in 1965/66 and were numbered 7031-48; 'phase 2s' were built in 1970 and were numbered 7049-58.

The 4-BIG fleet were initially classified as Class 420 by British Rail, under the TOPS system introduced in 1968, and then Class 422.

8-MIG fleet

In 1983, two temporary 8-MIGs, given the TOPS classification Class 482 and numbered 2601/02, were formed while the 4-BIG fleet underwent asbestos removal. They were used on the Portsmouth Direct line; therefore, four standard 'Phase 2' 4-CIGs, numbers 7401–04, were reformed with a conventional locomotive-hauled miniature buffet carriage (RMB). Each 8-MIG 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 8-MIG was formed of 4-CIG + RMB + 3-CIG.

The formations of the trains are listed below:

These units were only used during the summer of 1983, after which enough asbestos-free 4-BIG trains were available. The two 8-MIGs were disbanded and the four 4-CIG was reformed. The 4-CIGs have since been renumbered several times:

8-DIG fleet

In 1992, four 8-DIGs, numbered 2001-2004, were formed by semi-permanently coupling a 4-CIG and a 4-BIG; these were dedicated to London Victoria to Brighton express services, which were operated as the Capital–Coast Express. The 8-DIGs were formed from four 'Phase 2' 4-BIGs plus two 'Phase 1' and two 'Phase 2' 4-CIGs. Phase 1' nos. 1901/02, were fitted with Mk.6 motor bogies. One of the 'Phase 2' 4-CIGs, no. 1875 (formerly 7404), had previously been part of 8-MIG no. 2602. The units were disbanded in 1996, after replacement by dedicated Class 319/2 EMUs. The various 4-CIGs and 4-BIGs were reformed and regained their original numbers, except no. 1875, which was renumbered to 1802.

South Eastern Trains

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

All but one of the 'Phase 2' trains continued to carry the Network SouthEast livery, which was obsolete by then. No. 1870 was repainted into Connex South Eastern 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, they remained in traffic for seven more years from 1997 to 2004. They were popularly known as Ghosts by rail enthusiasts.

From 2003, these trains started to be withdrawn, having been replaced by the second batch of the new Class 375 Electrostars. The three 'Phase 1' units had gone by mid-2004; the final train was no. 1843, which lingered on for several months longer than its classmates, eventually being withdrawn in mid-November 2004. All of SET's units have been scrapped.

South Central / Southern

This division inherited the largest fleet of 4-CIGs. Originally this included all remaining 'Phase 1' units, the 35 'Phase 2' and the four 8-DIGs. The remaining few 4-BIGs 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 as South Central; in 2004, this was changed to Southern. Four 'Phase 1' (nos. 1735/38/40, 1908) and eight 'Phase 2' trains (nos. 1854/56-62) received Southern's new green livery.

In 1997, the remaining 4-BIGs were withdrawn; eight were transferred to South West Trains and the remaining eleven trains were heavily rebuilt at Eastleigh railway works, with compartments removed and opened out, with the buffet carriages withdrawn. The modified trains were reclassified as Class 421/7 and were renumbered into the 1401–1411 range; they were also known as 3-COPs, 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:

• 1408: Littlehampton Progress 2000
• 1409: Operation Perseus.

In 2004, some trains were augmented to four carriages with the addition of a 'Phase 1' intermediate trailer; they then became 4-COPs.

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

South West Trains

South West Trains inherited a small fleet of twelve 'Phase 2' 4-CIGs and the larger fleet of 22 Greyhounds, which had been modified to cut several minutes from journey times on the Portsmouth Direct line. This route's 1 in 80 gradients were achieved by adding a second stage of field weakening to improve performance at higher speeds.

In 1997, the fleet was augmented with the addition of eight 4-BIGs 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 Greyhounds were converted from the redundant 4-BIGs. These 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 the mechanically-similar Class 411 4-CEPs. Most of these trailers came from 4-CEPs to make 3-CEPs, 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 premium InterCity70 seating. The buffet carriages were withdrawn, although many were saved for preservation.

In December 2004, no. 1394 was reduced to three-cars 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 no. 1198.

Withdrawals started in mid-2004, when many new Class 444 and 450 Desiro trains became available for service. By the end of 2004, just a handful of units remained in traffic; the final few 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 nose. 1396, 1398 and 4-VEP 3536. Following withdrawal, nos. 1304 and 1881, were transferred to warm storage for use by Southern if required. Most others 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 3-CIGs, nos. 1497 and 1498; they 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 they carried when built. However, in May 2010, the new timetable changes saw them replaced for more modern stock to save maintenance on a small non-standard fleet. 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 were replaced by a Class 158 on weekdays and a Class 450 at weekends. These two Class 421s have both been preserved, due to their historic significance.

Departmental service

Following withdrawal from passenger service, several vehicles have seen further use in departmental service:

• 3-COP no. 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 (formerly 1850) was converted into an ultrasonic test train vehicle for use by Network Rail; it was renumbered 999606.
• The rest of 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' 4-CIG no. 1749, was rebuilt as the Class 424 Networker Classic prototype in 1997. It was displayed to the public at London Victoria, paired with a legacy driving trailer 76747 from 4-BIG 2256 as a comparator. 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 by HSBC Rail from Shoeburyness for parts stripping at the Railway Technical Centre (RTC) in Derby, after which they went to C.F. Booth for scrapping.

Preservation

Two complete trains have been preserved, along with several buffet cars from 4-BIGs. The full list is shown below, with complete units highlighted:

• 'Phase 1' 1753 has been preserved by the Network SouthEast Railway Society and is stored at Nemesis Rail, Burton-upon-Trent
• 'Phase 2' 1497 has been preserved on the Lavender Line.

Former preserved CIGs, all 'Phase 2', included:

• 1304, later scrapped by the Brighton Belle Preservation Trust
• 1392, scrapped by the Brighton Belle Preservation Trust; its MBSO, in an extremely stripped condition, survives as a shell)
• 1393, later scrapped by the Great Central Railway; its MBSO is in use with Network Rail
• 1399, partially component recovered by owner in 2016 to provide spares float for 4-VOP 3905 and other projects; it was used in filming of 'Last Passenger'
• 1498, exported to Ireland for use as glamping accommodation.
• 1499, later scrapped by the Dean Forest Railway
• 1881, later scrapped by the Brighton Belle Preservation Trust; one DTS remains at Barrow Hill Roundhouse
• 1884, later scrapped by the Brighton Belle Preservation Trust.