Metropolitan Police staff will strike on Bonfire Night as a dispute over pay continues.
The Public and Commercial Services union (PCS) said almost 6,500 of its civilian staff members will walk out on November 5.
It comes as a row between the union and the Met over a London allowance paid to staff remains unresolved.
Members voted to walk out earlier this month after they were refused £1,250 in the allowance.
The PCS argued that 999 call handlers, detention officers and police community support officers should be given the same allowance value as Met Police officers.
Fran Heathcote, the union’s general secretary, said: "Rent, mortgage repayments, food prices and energy bills have been rising for everyone in London - so why does the Met treat its civilian staff differently to officers?
"To prevent any disruption to the vital services our members provide to the people of London every day, this payment must be paid immediately to civilian staff."
The move comes after around 300 Met staff walked out in a dispute over hybrid working in February.
Met Police officers are banned from taking strike action under the Police Act 1996, but this does not apply to the force’s civilian staff.
