He has also been an honorary fellow in mathematics in Aberystwyth University for many years and has had wide experience in different medical settings: general practice, teaching hospital departments with international reputations of excellence and district general hospitals in urban and rural areas. His insight is reflected in the content of the Oxford Handbook of Clinical Diagnosis based on his teaching notes when he was a consultant physician at King’s College Hospital in London and the mathematical models in the form of new theorems on which the book’s content is based.