British employees of US car giant Ford were staging a 24-hour strike on Monday in a row over pay and pensions.
The Unite trade union said the walkout from 0500 GMT would affect plants at Dagenham in east London, Bridgend in south Wales, Halewood in north-west England and Southampton in southern England.
Unite, which represents around 1,200 white-collar workers at Ford's British plants, said staff were "furious" at plans to lower their pay rates from next year and close the final salary pension scheme to new employees.
"To date Ford has failed to make any genuine attempts to resolve this dispute," said Unite national officer Roger Maddison.
"We fiercely oppose the closure of Ford's final salary scheme to new entrants because we believe ultimately Ford will try to close the entire scheme."
The dispute does not involve production workers, though Unite said it believed the strike would affect production.
A spokesman for Ford, the number-two US automaker, said the vast majority of the company's employees were not involved in the strike.
"Ford remains willing and available to continue discussions with the union representing these workers," he said.