Dr Clarke is a Consultant Neurologist with a special interest in high altitude medicine and cold injury - he has been in consultant practice since 1979. He has run an international information service for altitude medical problems and cold injury.
He has spent 40 years involved in mountaineering and throughout his careers has had an interest in the effects of chronic hypoxia in man and medical problems of high altitude in which he qualified. He has been Honorary Medical Officer to the British mountaineering council and was a medical representative of the risk management committee of outward bound. He is also a founder member of the international society for mountain medicine.
He initiated, edited and produced with three neurology colleagues, the textbook neurology: A queen square textbook.