The Class 455s were the first train type on the South London Metro to be fitted with passenger operated automatic sliding doors, this development revolutionised the commuter services where they operated by drastically reducing dwell times compared to the slam door trains they replaced. The Class 455s were built over three batches, all with differences between them. The first batch of 74 units operated both the South Central and South Western inner suburban commuter lines. The second batch of 43 units have a revised front end and make use of redundant trailers from the Class 508 fleet instead of having new build Mk3 type trailers. The third and final batch of 20 units are identical to the second however with new build Mk3 type trailers, as well as the second batch these operate exclusively on the South Western inner suburban commuter network out of London Waterloo.

Since privatisation both the Southern and South Western units have both seen a series of major refurbishment programmes. The Southern units were refurbished during the mid 2000s, new high back seating was fitted as well as the removal of cab end gangways to allow for the installation of driver's cab air conditioning, these gave the units a more unusual look compared to their original design. The South Western units were refurbished at a similar time with similar, though not identical, high back seats fitted. In 2013 however South West Trains began replacing the original DC traction motors on their units with a new AC system, as well as a completely new braking system. This refurbishment saw a massive improvement to the reliability of the fleet, and saw a reduction in overall operating and maintenance costs.

In more recent times, Southern withdrew their fleet of 46 units completely in 2022 during the May timetable change of that year. South West Trains, now South Western Railway, have had to retain their much larger fleet into 2025 thanks to delays in the introduction of the new 701 Arterio trains. 455868 was returned to a variation of British Rail Blue Grey livery in 2024, during regular maintenance at Bournemouth Depot. The repaint was done to celebrate their 42 years service and the people who have worked on them. 455868 is currently out on the South Western network operating services on most days, information on it’s whereabouts can be found on RealTImeTrains by searching the unit number.

(1) Southern 455845 at London Bridge. (2) Network SouthEast 67300 (Ex Networker prototype 457001) at Sheperdswell on the East Kent Railway. (3) South Western Railway Class 455s 713, 725, 868, 920 and 717 at London Waterloo. (4) Southern 455836 and 455834 in storage at Hove Yard. (5) South Western Railway 455710 approaching Earlsfield.

Additional information on the Class 455

South Western Railway: Class 455

https://www.southwesternrailway.com/travelling-with-us/our-trains/class-455

Southern Railway Group - Class 455

https://sremg.org.uk/emu/class455.shtml