“I may not have any faith in Lord Mandelson, but I actually do believe, in prior discussions with both preferred bidders, he has secured a sufficient enough pledge of commitment to ensure the Ellesmere Port plant has more than just a short-term future.

“That cannot be said of the Luton van plant, though. With contracts running out over the next two years from Nissan and Renault and with no sign of any likely pick-up in van sales, the future for Luton looks to me pretty bleak.”

Mr Wheeldon also said the UK government would need to offer financial guarantees to GM Europe to ensure Ellesmere Port’s future.

He said: “Given that this is probably the most highly-invested of the four specific car production plants under the Opel/Vauxhall brand names, it seems to me that continued production here looks reasonably assured over the next three to four years.

“No guarantees, of course, but it seems to me whoever acquires the final rights of GM Europe would be entitled to expect the British government provides adequate short-term financial resources, rather than relying on Lord Mandelson’s moral support.”

The remaining bidders for GM Europe are Italian car giant Fiat and Canadian car parts maker Magna International.

Unite’s Merseyside-born joint general secretary, Tony Woodley, said yesterday: “The UK government must now finish the job it has been working on. That means being at the meeting table when the final decisions for the ownership of GM Europe are made. The future of our plants and jobs are at stake.

“Germany will be thinking strategically about manufacturing, not just for the next two years but the next 25 years. I believe the British government should be doing the same.

“It is crucial we do not allow any other government to drive through a plan which reflects only one country’s interests.

“We also need to make sure that we put British money up.”