Around 40,000 members of railway staff who belong to the RMT Union are taking part in a strike over pay and job security.
The one-day strike (Wednesday, July 25) is due to hit Network Rail and 14 railway firms throughout the country, including Great Northern, Southern and Thameslink.
Govia Thameslink Railway has released its timetable for the strikes, but company officials are urging passengers not to travel unless they have to.
A GTR spokesperson said: "Please only travel if your journey is absolutely necessary, and expect severe disruption.
"The railway will operate limited opening hours with services starting later than normal and finishing in the late afternoon.
"Journey planners have been updated, so please check your first and last trains, as there will be no alternative travel outside of these services.
"Any engineering works planned for this day will not take place, but please ensure you check the service information below for what services will be running."
On Thursday, July 28, the spokesperson said trains will not run before 7am, with a Sunday timetable in place.
GTR has launched "Industrial Action" pages on its
websites: https://www.thameslinkrailway.com/industrialaction
North of the River Thames in London, the GTR timetable for Wednesday, July 27 features:
King’s Cross, Cambridge and Ely
- One train per hour will run between King’s Cross and Ely, calling at King’s Cross, Finsbury Park, Potters Bar, Hatfield, Welwyn Garden City, Welwyn North, Knebworth, Stevenage, Hitchin, Letchworth Garden City, Baldock, Ashwell & Morden, Royston, Meldreth, Shepreth, Foxton, Cambridge, Cambridge North, Waterbeach, Ely
- One train per hour will run between King’s Cross and Cambridge, calling at King’s Cross, Finsbury Park, Stevenage, Hitchin, Letchworth Garden City, Baldock, Ashwell & Morden, Royston and Cambridge only
- One train per hour will run between Cambridge and Ely, calling at Cambridge, Cambridge North, Waterbeach and Ely only
King's Cross, Welwyn Garden City and Peterborough
- Two trains per hour will run between King’s Cross and Peterborough, calling at King’s Cross, Finsbury Park, Stevenage, Hitchin, Arlesey, Biggleswade, Sandy, St Neots, Huntingdon and Peterborough only
- Two trains per hour will run between King’s Cross and Welwyn Garden City, calling at King’s Cross, Finsbury Park, Harringay, Hornsey, Alexandra Palace, New Southgate, Oakleigh Park, New Barnet, Hadley Wood, Potters Bar, Brookmans Park, Welham Green, Hatfield and Welwyn Garden City
King's Cross, Hertford North and Stevenage
- Two trains per hour will run between King’s Cross and Stevenage, calling at King’s Cross, Finsbury Park, Harringay, Hornsey, Alexandra Palace, Bowes Park, Palmers Green, Winchmore Hill, Grange Park, Enfield Chase, Gordon Hill, Crews Hill, Cuffley, Bayford, Hertford North, Watton-at-Stone and Stevenage
St Pancras, St Albans, Luton and Bedford
- Two trains per hour will run between St Pancras International and Bedford, calling at St Pancras International, West Hampstead Thameslink, St Albans City, Harpenden, Luton Airport Parkway, Luton, Leagrave, Harlington, Flitwick and Bedford only
- Two trains per hour will run between St Pancras International and Luton, calling at St Pancras International, Kentish Town, West Hampstead Thameslink, Cricklewood, Hendon, Mill Hill Broadway, Elstree & Borehamwood, Radlett, St Albans City, Harpenden, Luton Airport Parkway, Luton
Great Northern between Finsbury Park and London Moorgate
- No trains
Great Northern between Ely and King's Lynn
- No trains
Southern between Watford Junction and Croydon
- No trains
Thameslink in central London
- No trains between London St Pancras and London Bridge, through Farringdon
- No trains between Finsbury Park and London St Pancras
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