London Underground (LU) has commenced legal action challenging the validity of the strike called by the Aslef union in a row over additional Boxing Day pay.

Aslef is calling for “substantial incentives”, thought to be treble pay, and a day off in lieu for those that work on Boxing Day. If the dispute is not resolved, the union intends to take further action on 16 January and 3 and 13 February.

The crux of LU’s legal action to block the strike is that, despite only a quarter of LU’s 3,500 drivers being scheduled to work on 26 December, Aslef has balloted all 2,200 of its members for strike action.

Howard Collins, LU’s Chief Operating Officer, said: “This threat of strike action is disgraceful, and Londoners will share our disbelief at these outrageous claims by Aslef’s leadership for even more money to work on a day for which their members are already being paid.

“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.”

An ASLEF spokesperson said the union was not surprised at the legal challenge, but it was disappointed.

They commented: “I am sure Londoners would prefer LU to be sitting down with the union hammering out a solution to this dispute rather than wasting time briefing solicitors and wasting money by pouring it into the pockets of barristers.

“We don’t expect the legal challenge to be successful and all it will do is increase ill-feeling which will make an agreement more difficult to secure.

“Legal action at this time is no more than a distraction.”

A High Court decision is expected today.