Staff are working flat out amid 'very substantial pressures', ambulance boss Dr Anthony Marsh said as he met MPs in Westminster in the wake of historic missed targets and staffing problems at the beleaguered NHS Trust.

He said the service continued to make progress and was no longer one of the worst performing in the country, with average response times 'substantially reduced'.

He told MPs that recruitment of paramedics had also been successful.

Dr Marsh, and board chairman Sarah Boulton, were in London as part of a regular update.

The chief executive is set to leave the Trust later this year, and Ms Boulton told MPs that the board would advertise for his role later this month, with interviews set to take place in June.

The meeting came as figures collected by UNISON showed staff do not feel supported by the trust chair Sarah Boulton and non-exeuctive directors.

She said: 'Obviously, as a board, we would like to be in a position where we are meeting all the statutory targets at this time. That would have been our expectation, but if you look at our plans for the year, you will see we had not planned, and neither had our commissioners, for the high level of demand that we have experienced. If you look nationally it is the same story. We would have liked to have done a lot better.'

But she said the investment in front line resources had been a 'major achievement'. She also said board members had been 'out and about' meeting staff in each of the six areas of the service to find out about their issues.

'They do have issues, and a lot of that is because of high levels of demand. Late finishes for example. Consistent late finishes are very unpopular and very bad for staff morale.

'That partly reflects those high levels of demand over Christmas. It is a key reason why we need to be much better at bringing that extra resource in. 'We will not be so stretched in terms of meeting the targets as we get the student paramedics in post and working full time. At the moment they are still in training.'