The heads of two Midland ambulance services facing merger are quitting amid accusations that the plan is a "done deal".

The resignations of Barry Johns, chief executive of West Midlands Ambulance Service and Britain's longest serving ambulance service boss, and Staffordshire's Roger Thayne were announced yesterday.

It came the day after the Prime Minister insisted no decision had been made on a merger of the West Midlands, Staffordshire, Coventry and Warwickshire, and Hereford and Worcestershire ambulance trusts into a new service, called Central West.

But The Birmingham Post can reveal that even though the proposals are out to public consultation - which is due to end later this month - Anthony Marsh, currently chief executive of Essex Ambulance Service, has been appointed to lead the new Central West region from July 1.

The chief executives of the four existing trusts are all believed to have applied for the new post and Mr Johns said his failure to land it had been a factor in his decision to leave WMAS after 25 years at its head.

The Government plans to merge 31 ambulance trusts in England and Wales into ten larger services.

Mr Johns, who began his career as a paramedic in Plymouth in 1968 and will step down on June 30, voiced dismay that no Midland applicants had been appointed to any of the new ten interim chief executive posts.

"I went for the new job and I didn't get it, so that's part of the reason I'm leaving," he said.

"We've not done very well out of this. We've had no particular feedback as to why no applicants from the Midlands region were appointed to any of these new roles.

"However, I think it's appropriate that as WMAS will cease to exist after June 30, then so will my role in that organisation."

He added: "I am confident of a bright and exciting future for the new ambulance service trust, and I genuinely believe this is the right thing to do."

Mr Thayne had previously vowed to quit his job if the merger went ahead. He announced yesterday that he will leave at the end of this month.

He was not available for comment yesterday but Lichfield Tory MP Michael Fabricant, who is campaigning for the Staffordshire service to retain its status quo, said: "His resignation is a personal shock and, I fear, a reaction to the Government's plans to merge the Staffordshire Ambulance Service in with the West Midlands.

"Under Roger's leadership the Staffordshire Ambulance Service has out-performed all other ambulance services in Europe with the fastest response times to emergency calls.

"Despite the Prime Minister's assurance on Wednesday and Patricia Hewitt's, the Health Secretary's, assurances that the merger has yet to be decided, I fear that this is a done deal.

"So I will be collecting a petition on Friday from Lichfield City Council urging that our ambulance service be kept and will be passing it on to the Health Secretary."

Mr Thayne's departure follows his part-time secondment as interim chief executive for the Wales Ambulance Service.

A Staffordshire Ambulance Service spokesman said: "Roger's time with this county's ambulance service and his achievements with his management team and ambulance staff can and should not ever be underestimated.

"Staffordshire has gained not just national recognition but a worldwide reputation for innovation and most of all for its phenomenal life-saving records."