Serious disruption on Gatwick Express, Southern and Thameslink services between London and Brighton is expected to continue all day.
"In the early hours of this morning, an engineering train broke down at Horley whilst carrying out Bank Holiday engineering work," National Rail said.
"Network Rail were unable to gain access to fix and remove the broken down engineering train due to the morning peak. They are now on site and the broken engineering train has moved and is now completing the engineering works. This has eased congestion in the Gatwick Airport area but we will continue to monitor the service.
"One of the London bound and Brighton bound lines still remained blocked. Platform alterations are still expected between East Croydon and Gatwick area while the lines remain blocked. Customers are advised to expect platform alterations and to check the boards and listen out for announcements."
Train services currently running through these stations may be cancelled or delayed by up to 40 minutes. And while it is estimated that the works will be completed to provide a normal service with a few alterations during the evening peak, National Rail said disruption is expected until 8pm.
|National Rail customer advice|
To try and minimise disruption, the train service has been amended as follows:
Alternative Travel Options
Gatwick Express, Southern and Thameslink customers may use each others' services between London and Brighton.
Southern customers may use: