He said: “North Middlesex University Hospital NHS Trust has a committed and professional group of clinical staff who are strongly supported by equally committed non-clinical staff. My chairmanship has been a very satisfying and challenging experience.

"I have attempted to ensure the delivery of high quality service to local people in the context of financial constraints. It has been a pleasure to work with a very motivated executive team and some experienced and highly motivated non-executive board directors.

“I particularly appreciated visiting and speaking to staff during my walkabouts in wards and departments. Also chairing consultant and executive appointment committees for the insights it gave me into the high standards of senior surgical, medical and nursing staff.

“There have been some difficult times but the hospital is now on a positive trajectory with a growing sense of confidence. I am proud to have been part of the long history of service to the local community and wish all patients, staff and non-executive directors, well in the future.”

A former Camden councillor, he took his first unpaid NHS role in 1974 when he became chairman of Camden Public Health Committee.

As part of his long string of continuous work for the NHS, he worked as vice-chairman at Hampstead Community Health Council and at then took over as chairman at the Royal Free NHS Hospital in 1997.

Subsequently he chaired the Camden Primary Care Trust and the North East London PCT Cluster before joining North Middlesex University Hospital’s board in May 2013.

Chief executive there, Libby McManus said: “John is an exceptionally dedicated individual. He has been an energetic and strong supporter of the hospital, our staff and patients through some challenging times.

“He has steered the board towards achieving the best results for our patients and staff. The whole hospital will join me in thanking him for his great contribution and we wish him well in all his future commitments to public service.”

A new chair of board will be appointed by NHS Improvement and will start on February 1.