Politicians have reacted with fear and concern after it emerged the interim chief executive of the region's ambulance trust has left his position.

Today the EDP and Evening News exclusively reveals Dr Anthony Marsh has departed from East of England Ambulance Service Trust (EEAST) despite the trust not yet having appointed a new chief executive.

In his final message to staff Dr Marsh urged workers to 'hold their heads high' and continue their dedication to clinical quality and patient standards.

He said: 'I am immensely proud of what we have achieved and you have proven you can turn the organisation around.

'There is still work to be done but I have total faith you can do it.'

An EEAST spokesman said Dr Marsh's departure was a 'joint decision' and added the trust expected to announce a new chief executive this month.

Dr Marsh joined EEAST as interim leader in January 2014, balancing the job with his role as chief executive at West Midlands Ambulance Service Trust, and has played an important role in attempting to turn around the trust's fortunes after it was criticised for slow response times.

It was announced in December 2014 he would leave once the trust had found a replacement.

In his message to staff Dr Marsh said: 'It hasn't been all about one person, this is an organisation of more than 4,000 staff and 1,500 volunteers and you have all contributed to making the crucial improvements we needed to make.

'You have proven what you are all capable of doing and I hope that you continue along this path you have started.'

His departure comes less than a month after nine frontline staff travelled to London to meet eastern region MPs to discuss issues around late finishes - and present a petition signed by hundreds of EEAST workers calling for Dr Marsh to remain in post.

Last night two of those Norfolk MPs said they were concerned over Dr Marsh's departure.

North Norfolk MP Norman Lamb was one of the MPs who met staff in London in July.

Mr Lamb, whose constituency has long endured poor response times, described Dr Marsh as one of the most experienced ambulances leaders in the country and said he thought the decision was a mistake.

He said: 'I can't hide my frustration. I have real concerns.

'I think it's a mistake to make this change while the trust is in a fragile state.

'We have to hope that the new chief executive can maintain the momentum that has been established and he or she will have my backing.

Clive Lewis, Labour MP for Norwich South, also met the staff in London and yesterday said Dr Marsh's departure was a 'sad day' for the trust.

'From talking to the staff in London they said that there is still a lot of work to do to keep improving, and the best person to enable that is Anthony Marsh,' Mr Lewis said.

'It is the staff on the frontline that understand the reality and I think their opinion really matters.'

He said his fear was that Dr Marsh was effectively made to leave the trust because he 'wasn't a yes man,' and that the trust would hire someone far more management orientated.

A spokesman for the trust confirmed that Dr Marsh returned to West Midlands Ambulance Service Trust last Wednesday.

The spokesman said: 'The trust is in the process of recruiting a new chief executive.

'The final interviews have been completed and the trust is in the process of agreeing final terms and arrangements for an appointment.

'We will make an announcement when this appointment can be confirmed, but the trust is aiming to have the new chief executive officer in post in August.'

Sandy Brown, deputy chief executive and director of nursing and clinical quality, will cover the chief executive post in the interim.

•Do you work for the trust? Email your views to nicholas.carding@archant.co.uk