Train passengers have been warned to expect disruption on Sunday due to staff shortages caused by hot weather and the World Cup Final.
Great Western Railway (GWR) warned a "significant number" of its trains would be without crew.
Northern, which will operate an amended timetable, said some of its staff were not required to work on Sundays and had "made themselves unavailable".
Other rail operators told the BBC they expected to run services as normal.
GWR has lifted ticket restrictions to allow travel on a different day.
Passengers have been advised to check websites for revised timetables.
Northern said it was still working on its plans, but warned that many services in Cumbria, Lancashire and Greater Manchester were likely to be cancelled.
GWR said the worst-hit services would be long-distance routes, including those to and from London Paddington, Bristol, South Wales, Oxford, and Devon and Cornwall.
It blamed factors including the World Cup Final, good weather and the start of the summer holidays, while Northern said staff did not have to give a reason for not being available.
Managing director Mark Hopwood said: "We will have managers and volunteers throughout our network to help at stations and on board, but unfortunately we will not be able to deliver our planned timetable of services; and the trains we are able to operate will be extremely busy.
"I would encourage customers to travel on a different day if they are able to and we will happily offer refunds to those who choose not to travel."
Other firms have told the BBC said they expected to run a normal timetable on Sunday.
- GTR (Southern)
- East Midlands Trains
- West Midlands Rail
- South Western Railway