Mary Edwards, the chief executive of Hampshire Hospitals Foundation Trust for more than a decade, has announced she will stand down at the end of the year.

Ms Edwards has worked at the organisation for 21 years, joining as director of nursing in 1995 and being appointed chief executive in 2003.

She took North Hampshire Hospitals to foundation trust status, and led the acquisition of Winchester and Eastleigh Healthcare Trust which created Hampshire Hospitals in 2012.

In the last couple of years Ms Edwards’ strategy for the organisation has centred on controversial plans to build a new “critical treatment hospital”.

Hampshire Hospitals’ commissioners are against the proposal, which they claim is “not affordable”.

Elizabeth Padmore, the trust’s chair, said Ms Edwards had made a “truly significant” contribution to the organisation.

“Her trademark approach, and one of the keys to her success as a leader, has been to support senior clinical staff to enable them to implement service developments that are clinically led and patient-focused,” she said.

“Mary’s drive, her vision and her ability to bring people together means she leaves behind a resilient organisation. I am now focused on the challenge of finding a new chief executive who will take forward the positive culture Mary has created and who can build on Mary’s success.”

Ms Padmore said the trust would pursue a “clear strategic vision for the future that will deliver sustainable service change including 24/7 consultant care for the sickest”.

Ms Edwards said: “Deciding to retire after so many years of service was tough because of the loyalty I feel to the staff and because I recognise the huge commitment shown by all of our staff, who come to work every day to deliver the best possible service to our patients.”

She added: “After a lot of thought and discussion with my husband, we have decided to prioritise our plans for retirement together.”

The Hampshire Hospitals board has started looking for a new chief executive, and expects to make an appointment by the end of the year.