Nationwide pay strikes by rail workers are expected to affect services across the country today (Thursday 18 August) and on Saturday.
Govia Thameslink Railway (GTR), which runs Southern, Thameslink and Gatwick Express services, warned people: “Only travel if your journey is absolutely necessary.”
The company added: “We’re really sorry if your journey plans are affected.”
GTR hopes to run services on the Brighton main line to London Victoria and London Bridge but not east or west coastway services.
The company said: “We are running a very limited service, with services finishing much earlier than normal and we are expecting severe disruption.”
Services would also be affected tomorrow (Friday 19 August) and on Sunday, the company added.
It said: “Only travel if your journey is absolutely necessary. Trains will start later than normal, will be extremely busy and you may not be able to board.
“Please be aware TfL (Transport for London) are also affected by strike action on Friday 19 August. “If you must travel, always check your journey immediately before at National Rail. If your journey crosses over with any other operator you should check their website for their travel advice.”
Today and on Saturday, only about a fifth of normal services are expected to run and half of all lines will be closed.
Trains will only operate between 7.30am and 6.30pm on both strike days and will start later than normal on mornings after.
Thameslink will not only run far fewer trains than normal but plans to split services north and south of London, with nothing running between London St Pancras and London Bridge.
And the Gatwick Express has suspended all services although GTR said that passengers travelling to or from Gatwick Airport should be able to use Southern and Thameslink trains.
Yesterday, GTR said that services on Southern, Thameslink and Gatwick Express routes could be disrupted until 11pm, with delays of up to an hour.
The company said that he “major disruption” resulted from a number of incidents including a death on the line between Bedford and St Pancras International and a fire near London Bridge.
Further problems arose when a tree branch came into contact with overhead wires near Hatfield.