The British Rail Class 321 electric multiple units were built by BREL York in three batches from 1988-1991. The design was very successful and led to the development of the similar Class 320 and Class 322 units for use by Strathclyde PTE and Stansted Express respectively. The bodyshell design was also used for construction of the Class 456 DC units.
The first batch of 66 units, built 1988-1990, were classified as Class 321/3. Units were numbered in the range 321301-366, and had a maximum speed of 100 mph. Each unit consisted of four carriages; two outer driving trailers, one of which contained 1st-class seating; an intermediate motor coach with 2nd-class seating only; and an intermediate trailer with 2nd-class seating. The technical description of the formation is DTCO+MSO+TSO+DTSO. These units were delivered in two groups, with individual vehicles are numbered as follows:
|Units 321301-346||Units 321347-366|
These units were built for outer-suburban trains on the Great Eastern Main Line, primarily from London Liverpool Street to Southend-on-Sea, Ipswich, Harwich, Colchester and Clacton-on-Sea. They replaced the ageing slam-door Class 305, Class 308 and Class 309 units on trains to Clacton and Southend, and worked services on the newly electrified routes to Ipswich and Harwich. They also displaced many Class 312 slam-door units to the LTS Line. Some of the Class 309 "Clacton Express" units were retained until 1994, and 24 of the newer Class 312 units were retained long-term to work services to Walton-on-the-Naze and peak services to Clacton, Ipswich and Witham. Units carried the distinctive Network SouthEast livery from new.
The second batch of 48 units, built 1989-1990, were classified as Class 321/4. Units were numbered in the range 321401-448, and again had a maximum speed of 100 mph. The formation of these units is identical to that of the first batch. Thus each unit was formed DTCO+MSO+TSO+DTSO. These units were delivered in two groups, with individual vehicles numbered as follows:
|Units 321401-430||Units 321431-442||Units 321443-448|
These units were built for outer-suburban services on the West Coast Main Line, from London Euston to Watford, Milton Keynes, Northampton, Rugby, Coventry and Birmingham New Street. Units were delivered in Network SouthEast blue, red and white livery. They displaced the slam-door Class 310 units dating from 1965, and Class 312 units dating from 1977. Both of the displaced types moved to the LTS Line.
The final batch of three Class 321/9 units were built in 1991 as an add-on to the main batches. These units have a similar formation to the earlier units, except that there is no 1st-class seating. Therefore, the formation is DTSO+MSO+TSO+DTSO. Units are numbered in the range 321901-903, and individual vehicles are numbered as follows:
- 77990-77992 - DTSO
- 63153-63155 - MSO
- 72128-72130 - TSO
- 77993-77995 - DTSO
Due to a delay in the units entering traffic, five redundant Class 307 units were introduced on the route as a stop-gap measure in 1991. These elderly units continued in service until 1993, when the Class 321 units finally entered traffic. In 1994, they were joined by several Class 308 units, which were introduced on serviced around Leeds following electrication of the Aire Valley routes to Ilkley, Skipton and Bradford.
Following privatisation, the Class 321 fleet was divided between three franchises.
Arriva Trains Northern / Northern Rail
First Great Eastern / 'One' Railway
First Great Eastern inherited all 66 Class 321/3 units and 11 Class 321/4 units.
3 Class 321/3 units have since been transferred to Silverlink to accommodate the loan of units to Central Trains.
Silverlink inherited the 37 of the 48 Class 321/4 units. The remaining 11 units had been transferred to the Great Eastern region some years previously.
In December 2004, London Euston - Birmingham local services were divided into 2 self contained services: Silverlink retained Northampton - London, with Central Trains taking over all local services between Birmingham and Northampton. To begin with Central hired in several Class 321s from Silverlink to work their new services, but with the arrival of the new Class 350 "Desiro" units, very few units are now required.
To accommodate this sub-lease, 3 Class 321/3 units were transferred from One Railway to Silverlink. These are not permitted north of Northampton and therefore cannot be used on Central Trains services.
|Class||No. Built||Year Built||Number Range||Operator||No. in Traffic||Current Units|
|Class 321/3||66||1988-1990||321301-366||'One' Railway||66||321301-366|
|Class 321/4||48||1989-1990||321401-448||'One' Railway||11||321438-448|
|Class 321/9||3||1991||321901-903||Northern Rail||3||321901-903|