London Underground is seeking a High Court injunction to stop Boxing Day’s strike by Aslef members from going ahead.
Union members voted for strike action in a dispute with LU over additional payments and a day off lieu of working on the bank holiday.
Three additional strikes are planned for 16th January, 3rd and 13th February.
LU says it will be challenging the validity of Boxing Day’s strike strike which was backed by 42 per cent of Aslef members.
Last week the union said: “The whole dispute has been about seeking equitable quality time off for our members but recognising those who do operate the service may need to be incentivised.”
Howard Collins, LU’s Chief Operating Officer, said: “LU has a long-standing agreement with all of its trade unions which covers working arrangements on public holidays, and Boxing Day is included in that.
“The Underground is a public service that should be playing its part in helping Londoners and the Capital have a happy and prosperous Christmas, and we will take every possible step to ensure that happens.”
The court hearing will take place later this week.