Rail workers at two companies are staging fresh strikes in the long running dispute over guards on trains, causing travel misery for last-minute Christmas shoppers.
Members of the Rail, Maritime and Transport union (RMT) on South Western Railway (SWR) and Arriva Rail North (Northern) walked out on Saturday for 24 hours.
It is the 41st strike on Northern, with more planned every Saturday until the end of January.
More strikes will be held on SWR on December 27 and New Year's Eve.
Picket lines have been mounted outside stations, while services by both operators are reduced.
SWR said in a statement: "By targeting the last Saturday before Christmas when people are trying to travel to be with family and friends, the RMT is ensuring the maximum misery is inflicted at what should be a time of relaxation and enjoyment.
"This action is totally unnecessary. We have guaranteed to roster a guard on every train, and we need more, not fewer guards - 70 more by May 2019 - and we have an opportunity with the introduction of the new suburban trains to operate these trains differently to maximise the customer benefits."
'A vital period for businesses'
Northern said very few of its services will run after 5pm, with trains expected to be "extremely busy".
Managing director David Brown said: "By the end of December, we will have had 19 consecutive Saturdays of RMT strike action.
"This targeted action disrupts our customers' lives, but as we enter a vital period for businesses, it also damages the economic wellbeing of the north of England.
"We have fantastic colleagues who have supported customers by keeping our trains running on each of the RMT strike days.
"We are aiming to keep as many people moving as possible and ensuring customers can still travel into the biggest towns and cities for the big seasonal events including Christmas markets - but with very few services running after 5pm.
"We expect all of our services, and those of other operators, to be extremely busy and are calling on our customers to plan their travel carefully for the coming weekend, check the new timetables well in advance, and make sure they do not rely on the last trains home."
RMT general secretary Mick Cash said: "I want to pay tribute again to RMT members across Northern Rail on this 41st day of strike action.
"It is their sheer guts and resilience that has kept the fight for safe and accessible rail travel for all across the Northern franchise in the spotlight while the company continue to duck and dive and refuse to face up to the key issues.
"While the company resort to desperate PR stunts it has only been the determination of RMT members and our supporters from the travelling public whose solidarity has been instrumental in keeping the focus of the dispute on the campaign for a guaranteed second person on the train with the full suite of safety competencies.
"We thank the public for their continuing support and understanding in a dispute which is about putting rail safety before private profit."