Staffordshire Ambulance Service - the only Midlands trust to stay unchanged after recent mergers - could be merged into the new West Midlands service as early as December, it was suggested yesterday.

A Department of Health schedule aims to incorporate Staffordshire into the enlarged West Midlands Ambulance Service by December 31, 2007 - but the trust's new chief executive believes it could happen sooner.

Anthony Marsh, formerly chief executive of Essex Ambulance Service, said fears Staffordshire's performance levels would fall if merged with the three Midlands trusts were unfounded.

Roger Thayne resigned from his post as chief executive of Staffordshire Ambulance Service in March, over fears the merger would be "an unmitigated disaster".

But Mr Marsh, who turned zero-rated Essex into a top flight trust in three years, is determined to make the new service the best in the UK.

Mr Marsh, aged 41, who took up the post last month, said: "The directions handed down show the merger with Staffordshire should take place by December 31, 2007, but that could happen sooner, maybe by the end of this year. If there's a good case for doing so, why would we delay?"

The "ambiguity" around whether Staffordshire would retain independence or merge delayed the process of appointing joint directors for human resources, finance, information management and procurement.

"Roger Thayne has always been very clear the model used in Staffordshire could not operate on a larger scale, hence his fears their performance could be affected," said Mr Marsh. "But, in performance terms, Coventry and Warwickshire are only two per cent behind and Oxfordshire is also on a level pegging with them, so I don't believe Roger's fears are founded.

"Not everything good happens in Staffordshire. There's lots of good things happening within our area, including Coventry and Warwickshire, and Hereford and Worcester.

"The history between West Midlands and Staffordshire is an issue but it's not a problem that cannot be resolved."

He added: "When I was appointed chief executive of Essex Ambulance Service, it was a zero-rated trust, but within three years it had achieved a three-star rating and become one of the best in the country. I want to do that for West Midlands now."