It comes as Northern is proposing to introduce an amended Sunday timetable in the North West next month.

The train operator says it is to provide passengers with more certainty about those services it will be able to run and to reduce the number of short-notice cancellations.

The amended timetable, which Northern hopes to introduce from Sunday 22 December, will have fewer services on Sundays in the North West.

The proposed changes to the Sunday timetable comes after RMT members rejected Northern’s enhanced four-month pay offer for conductors to work on Sundays during a recent referendum vote – an offer that would have seen them double the money they get for working on Sundays.

The situation with conductor availability is expected to worsen over the Christmas period, with fewer conductors volunteering to work extra shifts or overtime.

Network Rail has also announced engineering projects will affect services on various routes across the Northern network.

If Northern is forced to cancel services, it will look to provide rail replacement services for customers where possible.

For all the latest information on routes affected by engineering works, ticket acceptance and refunds, customers are asked to visit: northernrailway.co.uk/christmas-engineering.

Matt Rice, chief operating officer at Northern, said:

“We are disappointed that our offer for conductors to work on Sundays was rejected and we would like to say sorry to everyone in the North West who will be affected by this disruption in the run up to Christmas.

“We believe the deal that was put to RMT members was fair and reasonable and, if it had been accepted, would have improved reliability in the short-term while we worked with the RMT to secure a longer-term agreement.

“Despite this setback, we will continue to work with colleagues and the RMT union to find a new way forward.

“Our performance in the North West has not been good enough for some time and we understand the impact it has on our customers.”

He added:

“Across the rail network, Christmas period is an opportunity for Network Rail to carry out engineering. For those wanting to travel over this time, we are asking them to check their journey as close to the day or travel as possible to see if these works will affect their journey.”

Northern currently employs more than 2,000 drivers and 1,400 conductors – more than ever before – and enough to run its timetable. Like most train operators, Northern relies on some rest-day working and overtime to cover training, sickness, and other unavailability.

Sundays are currently outside the working week for most conductors with a notice period not to work Sundays allowed in the North West due to an agreement which was inherited by Northern Trains Limited when it was set up to run services in 2020.

Northern secured a separate rest-day working agreement for train drivers with the trade union ASLEF earlier this month.

Northern is the second largest train operator in the UK, with nearly 2,500 services a day to more than 500 stations across the North of England.