Civilian staff employed by the Metropolitan Police are being balloted for strike action in a dispute over office working.
The Public and Commercial Services union (PCS) said its 2,400 members are being ordered back to the office in the new year.
Depending on where they work, the increase in office attendance is from 40% to 60%, from 60% to 80% or from 80% to 100%, said the union.
PCS members working at the Office of National Statistics have previously voted for strike action over compulsory office attendance, while members at the Department for Environment, Food & Rural Affairs, and the Ministry of Housing, Communities and Local Government are campaigning for a four-day working week.
PCS general secretary Fran Heathcote said: “Yet again we are seeing an arbitrary figure chosen to decide how many days a week our members have to come into the office, when they are working perfectly well from home.
“There is no evidence people work better in the office. In fact, the opposite is true because workers are more productive when they have a better work-life balance, not having a stressful commute and able to spend more time with their family at home before and after work.
“It’s not too late for the Met to change their mind and return to the blended working model that has been so successful for many years.”
The ballot opens on November 6, with the result expected on December 10.
