A strike by staff at car giant Ford in a row over pay and pensions was said to be "extremely well supported" today.
Members of the Unite and GMB unions at sites across the country, including Halewood on Merseyside, walked out for 24 hours from 6am.
The unions said staff were "furious" at plans to close the final salary pension scheme to new starters and lower their rates of pay from next year.
Unite national officer Roger Maddison said: "Today's strike action has been extremely well supported by Ford staff and the message to management has been crystal clear. The Ford staff's strike committee will meet later this week to decide next steps.
"Our staff members will not stand by and allow Ford to create a two-tier workforce on pay and pensions. To date Ford has failed to make any genuine attempts to resolve this dispute.
"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. Ford must prove that it is committed to the UK by investing in its UK workforce. The UK has the best sales in Europe, there's no excuse to attack the terms and conditions of a new generation of Ford staff.
"The company is also refusing to back away from creating a two-tier workforce by making new starters work for less money for doing the same job as existing staff. This is totally unacceptable."
GMB national officer Justin Bowden said: "Talks with Ford last Friday, to avert the first national walkout in more than a generation, broke up with the company refusing to make any concessions in the dispute over closure of the pension scheme to new starters and 10% cuts in pay rates for new starters.
"Ford refuses to give assurances they will not close the pension scheme completely."
The dispute does not involve production workers.
Picket lines were mounted outside Ford plants by the striking staff, who include foremen, IT workers and those based in administration.
A Ford spokesman said: "The issue giving rise to the industrial action relates to a disagreement between the company and a particular group of its employees in relation to their ongoing pay and benefit negotiations.
"Ford remains willing and available to continue discussions with the union representing these workers.
"The vast majority of the company's employees are not involved in this disagreement, or the decision to take industrial action."