Trains in and out of London Waterloo will be disrupted today, due to a points problem at the station.
National Rail warned trains are expected to be delayed, cancelled or revised until the end of the day.
"Engineers carrying out testing of the signalling system at London Waterloo early this morning have located a fault in the points which control access to platform 13 at London Waterloo," the rail operator said.
A reduction in the available platforms means it is not possible to run all services as normal. As a result, some services may terminate and start back from different locations and some services may be cancelled.
South West rail services are affected. Customers have been advised that tickets will be accepted with the following operators:
Southern services between Dorking/Epsom and London Victoria
London Buses between Dorking/Surbiton and London Waterloo
London Underground on any reasonable route