Workers who clean trains for a number of train operators are to stage 11 days of strikes in a dispute over pay.
Members of the Rail, Maritime and Transport union (RMT) employed by contractors Churchill will walk out from April 27 to May 7.
They striking workers clean trains on Govia Thameslink, Eurostar, Southeastern and HS1.
The RMT is calling for wages to be increased and for cleaners to receive company sick pay and free travel.
In a recent letter to union members, RMT claimed workers had been offered a wage of £11.05.
The Living Wage for 2022 is set at £9.90 an hour, and the London Living Wage is £11.05.
General secretary Mick Lynch said: “Churchill have shown a complete disregard for key workers who were rightly considered heroes in the pandemic.
“With the profits Churchill makes, they could easily pay our members a fair wage, pay company sick pay and allow free travel across the network, just like directly employed railway staff.”