The interim chief executive of the region’s ambulance service left his position last week, it has been confirmed.

Dr Anthony Marsh was already chief executive of the West Midlands Ambulance Service Trust when he became the chief executive for a two-year period of the East of England Ambulance Service Trust (EEAST) in January last year.

And after 19 months in the role, in which he has been criticised over his £232,000 four-day-a-week salary and five-figure sums on expenses for hotels and taxis, Dr Marsh returned full-time to the West Midlands Ambulance Service Trust on Wednesday last week, the EEAST has confirmed.

It comes after the EEAST failed to hit national targets for response times for reaching the most seriously-ill patients in June.

Under NHS targets, 75% of 999 calls classed as Red 1 – life-threatening conditions where the speed of response may be critical in saving lives – should receive an ambulance response within eight minutes.

In the Ipswich and East Suffolk area, EEAST met the target in April (81.32%) and May (79.61%), but it dropped to 72.83% for June, meaning it missed the target for the first time this financial year.

In West Suffolk, the figure stood at 63.64% in June. It was a rise from 58.33% in April but a fall from 76.79% in May.

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.

Tim Roberts, regional organiser for Unison, said: “When Anthony came along, the EEAST was the worst-performing ambulance trust in the country and under his management there has been an increase in performance across the region.

“We were pleased with the number of frontline staff which he has been able to recruit and the investment in ambulances which he organised.

“But we are surprised that he has left before the trust has announced the name of his successor. We think it would have been better if he stayed in post and given an appropriate handover to his successor.

“From an experience point of view, it will be difficult to replace him, but we hope that his successor will have significant health experience to continue Anthony’s work because the ambulance trust is not out of the woods yet.

“It is has still got a number of issues. It is still experiencing quite a high turnover of staff, so even though they are recruiting new staff, a large number of experienced staff are leaving.

“There are still issues around the late finishes which our members have raised with us because there are not enough resources on the road and that means that a number of staff will be working 14-hour shifts which we think is a danger to staff and patient safety.

“We think the trust should do more about that, so the successor will have to get their heads around that quickly and resolve.”

In an open letter, Fraer Stevenson, Unison’s East of England branch secretary, said she was “very proud” of the achievements she has made a year into her position alongside Dr Marsh.

She said: “Gradually between us we built a sound working relationship, which as a new branch secretary I especially valued.

“Coming into a politically charged somewhat machiavellian working environment, after working in a close knit team of very caring people on the frontline, was far from easy.

“Although we didn’t agree on everything, we had an honest, trust based relationship which enabled us together to bring in many supportive changes for staff.

“Nationally, the ambulance sector is facing huge challenges and we have the absolute ability to change things for the better within our walls.

“We need a chief executive with vision, that’s brave enough to continue the work started and not be content with making sure we’re in the middle of the pack.

“If we move back to that ‘middle ground’ mentality, we’ll constantly be fire fighting, we’ll lose sight of the common purpose to better support our staff and we’ll likely see a lot more campaigning.”

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.