The chief executive of London Ambulance Service Trust is to retire at the end of the year.

Fionna Moore first joined the trust as medical director in 1997, became executive director in 2000 and then chief executive last year.

Dr Moore became chief executive during a difficult period for the trust. It was the first ambulance organisation in England to be put into special measures, last November, after an inspection from the Care Quality Commission in June 2015. The trust was ordered to bring its staffing up to safe levels and was rated “inadequate” overall.

Under Dr Moore’s leadership, the trust recruited more staff and increased training to tackle its staff shortage.

Trust chair Heather Lawrence said: “I want to sincerely thank Dr Moore for her years of service. Her leadership has helped steer the service through a challenging period and in the last two years she has overseen one of the biggest recruitment drives in NHS history: the development of the advanced paramedic practitioners programme.”

Dr Moore has more than 30 years’ experience in emergency medicine and has worked in the NHS for more than 40 years. Dr Moore was awarded an MBE in the Queen’s birthday honours in 2013 for services to the NHS and the emergency services.

She plans to spend her remaining weeks at the trust doing clinical shifts three days a week, including with the air ambulance.

She said: “I always wanted time at the end of my career to step back from management responsibilities and focus on my first passion, the clinical care of patients.

“It’s been a huge privilege to work alongside so many dedicated, committed and wonderful people for so many years. I am immensely proud of the work everyone at the service does and the progress we have made to improve our care to patients over the last 20 years.”

Andrew Grimshaw, the trust’s director of finance, will act as interim chief executive while the board and NHS Improvement are look to appoint a permanent chief executive.

NHS Improvement London regional director Steve Russell said: “For two decades, Dr Moore has devoted herself to London Ambulance Service. Her willingness to step into the chief executive role at a time of significant challenge for the organisation demonstrates her commitment to the service.

“Since taking up the role of chief executive, Dr Moore has led the delivery of clear improvements which form a strong foundation for the trust’s continued progress in performance, recruitment, and improved organisational culture. There is no doubt that the Service has further hard work ahead on its journey, but it has a sound platform on which build and grow.”