A slip coach or slip carriage is a British and Irish railway term for passenger rolling stock that is uncoupled from an express train while the train is in motion, then slowed by a guard in the coach using the brakes, bringing it to a stop at the next station. The coach was thus said to be slipped from its train. This allowed passengers to alight at an intermediate station without the main train having to stop, thus improving the journey time of the main train. In an era when the railway companies were highly competitive, they strove to keep journey times as short as possible, avoiding intermediate stops wherever possible.
If the express was on the centre track the coach was stopped short of the station and a shunter would move it to the right platform. Some trains would carry a number of these coaches to be slipped at different stations, and sometimes more than one coach would be slipped at one particular station. In some cases the coach would, after stopping at the intermediate station, then be attached to a branch line train to proceed to the terminus of the branch, so passengers from the express train for stations on the branch did not have to change. Special coaches were built for slipping, usually composite, containing accommodation of all classes, and would also contain a small brake section where a guard would operate the brakes and where parcels could be stored.
To reverse the journey, the passengers would board the slip coach at the intermediate station, which would then form part of a local train to the next station on the line where the express was scheduled to stop, and coupled to the express train there to be taken to its destination.
The first certain example of this practice being carried out was at Haywards Heath on the London, Brighton and South Coast Railway in February 1858. Improvements in the acceleration of trains, the introduction of fixed multiple unit trains, and the high cost per passenger of operating slip coaches, meant that the operation had mostly died out by the mid-20th century.
The Southern Railway abolished the practice in April 1932 with the electrification of the Brighton Main Line. The last two slip coach operations on the London and North Eastern Railway were out of Liverpool Street railway station in 1936. These were the 6 p.m. which slipped coaches for Waltham Cross using old GER 6 wheeled slip coaches and the 4.57 express to Clacton on Sea which slipped a couple of coaches at Marks Tey railway station for Bury St Edmunds railway station using a bogie corridor slip coach of modern design, with a corridor "trailer".
- Fryer, C. E. J. (1997). A History of Slipping and Slip Carriages. Usk: Oakwood Press. ISBN 978-0-85361-514-9.
- The Railway Magazine. July 1936.
- Rex Conway: Rex Conway's Steam Album, Sutton Publishing, ISBN 978-0-7509-4626-1