Train operators Southern, Thameslink and Gatwick Express urged passengers not to travel on Wednesday morning.
A “do not travel” alert by the UK’s largest railway franchise has been lifted but disruption is expected to continue throughout Wednesday.
Train operators Southern, Thameslink and Gatwick Express – all part of the Govia Thameslink Railway (GTR) franchise in south-east England – urged passengers not to travel on Wednesday morning “if at all possible” because of “multiple incidents”.
A train derailed near a depot in Selhurst, south-east London, and there was a fault with the signalling system between London Blackfriars and Norwood Junction.
⚠️We’re responding to a suspected derailment involving a train near Selhurst Depot, which is blocking the lines towards Norwood Junction and London Bridge
❌This is causing disruption to services in the area
👷There are no confirmed injuries at this time. Our teams are on site… pic.twitter.com/GIU0h0XF4j
— Network Rail Kent & Sussex (@NetworkRailSE) February 4, 2026
The “do not travel” alert was issued at 7.52am and withdrawn by 10am, but passengers were being warned that services may still be cancelled, revised or delayed by up to an hour.
Thameslink told passengers earlier: “A number of incidents across the Gatwick Express, Southern and Thameslink networks mean that all lines are disrupted.
“Trains across these networks may be cancelled, severely delayed by up to 60 minutes or revised.”
The latest information stated there was “significant disruption to Thameslink services today, and there is some disruption to Southern too”.
Network Rail released an image of the derailed Southern train showing that it remained upright.
It added there were “no confirmed injuries”.
The incident is preventing other trains from leaving the depot.
National Rail Enquiries said the signalling fault meant fewer rail lines were available for use between Norwood Junction and London Blackfriars, and that trains running on the available lines must travel at slower speeds than normal.
This means services are suspended on routes between: London Bridge and East Grinstead; Brighton and Cambridge; and Bedford and Three Bridges.
⚠️NEW: #Selhurst Disruption to London Overground services between Sydenham and West Croydon expected until 07:30https://t.co/i3qSKS6itV
— National Rail (@nationalrailenq) February 4, 2026
Several other Thameslink routes are also disrupted.
A GTR spokesperson said: “We’re very sorry for the disruption that customers have experienced this morning.
“A fault with the signalling system between Norwood Junction and London Bridge, along with a train derailment at Selhurst depot, are causing the disruption.
“We’re working with Network Rail to resolve these issues as quickly as possible.
“We advise customers to check our website and social media accounts for the latest travel information.”
Passengers whose journeys are disrupted are able to use tickets on certain alternative routes.
GTR, which also includes operator Great Northern, is the UK’s largest railway franchise in terms of the number of passengers carried.
Some 18% of train journeys in the UK are made on GTR services, according to the company.
Elsewhere on Britain’s rail network on Wednesday, a fault with the signalling system between Crewe and Sandbach means trains have to run at a reduced speed on all lines.
This is disrupting services between Crewe and Wilmslow, affecting Avanti West Coast, CrossCountry, Northern and Transport for Wales.
A signalling problem is also affecting South Western Railway services between Portsmouth & Southsea and Portsmouth Harbour.
