Trains from Brighton and Hove will be disrupted by strikes for three days in the coming month.
ASLEF, the train drivers’ union, has called the strikes because, it said, Southern Railway had refused to recognise Monday 28 December as a bank holiday.
Drivers will strike from midnight to midnight on Sunday 27 and Monday 28 December and again on Sunday 3 January.
The strike call, affecting services to and from London as well along the east and west coastway lines, follows a ballot of members.
Southern said in a press release: “We are extremely disappointed that ASLEF has called for strike action.
“We continue to work hard to avoid what would be an extremely disruptive strike for you, our passengers.
“ASLEF has chosen industrial action over negotiation in a dispute over Christmas working arrangements.
“We appeal to them to come back to the table and help find a solution for the sake of our staff (their members) and you.
“The union’s action is particularly frustrating as we are complying fully with the well established terms and conditions agreed with the union.
“These terms ensure that everyone gets two bank holidays over Christmas, in line with the norm for the vast majority of UK workers.
“For train crew, whose working week runs from Monday to Saturday, these two days will be Friday 25 December and Saturday 26 December.
“ASLEF, however, is demanding that Monday 28 December (a substitute bank holiday for those who do not have Saturday as part of their working week) to be treated as a third bank holiday for their members in order to attract increased rates of pay.
“We are committed to being fair to all our employees and not to favour any particular group in any way.
“However, we will continue to strive for a reasonable solution to ensure you are not inconvenienced and our staff are not put in the position of having to choose conflict over customer service.”