He qualified in medicine with an intercalated B.Sc. in 1990 at the Royal Free Hospital, University of London. He became a pilot with the
RAF University Air Squadron during his undergraduate training. He then trained in internal medicine, after which he took a research position with the Institute of Aviation Medicine in Farnborough. 

Dr. Mitchell completed specialist training in Occupational Medicine at Southampton University Hospital. During this time, he continued researching sensory perception in people with upper limb disorders. He joined the UK Civil Aviation Authority in 2000 and also earned a Diploma in Aviation Medicine. In 2002, he became Regional Medical Director for the Occupational Health Service for the London Fire Brigard and Capita Health Solutions. Subsequently, he returned to the Civil Aviation Authority and became the Head of the Occupational Health and Aeromedical Centre. He later also served as Head of Certification and Oversight, Head of Aeromedical Safety Systems and Emerging Technologies, and Head of Medical Regulatory Policy. 

Dr. Mitchell was Deputy Chief Medical Officer when he left the Civil Aviation Authority in 2022 to work for Qatar Airways as Medical Director. In 2025, he became a Senior Consultant AME at Heathrow Medical Services, where he was engaged in assisting to formulate a revised risk matrix for aeromedical certification. Within AsMA, he served on the Air Transport Committee from 2013–2021. An online obituary can be found at https://www.heathrowmedical.com/about-us/clinical-team/ at the bottom of the page.