Rail passengers have been told to avoid certain services for two weeks and that trains will be “significantly disrupted” across most of the country in the new year.
Network Rail’s warning came as some services came back to life on Tuesday after the Christmas shutdown and several days of strikes by members of the RMT union.
A combination of industrial action and engineering work meant trains started later than usual or not at all on Tuesday. Services between Cardiff and the Midlands and London Stansted Airport have been disrupted due to a strike at CrossCountry.
Trains are expected to be much busier than usual as the New Year approaches, ahead of a week of nationwide strikes by members of the RMT and Aslef unions from January 3.