John Creyghton Ainsworth-Davis was born on 23 April 1895 at Aberystwyth. His father was Professor of Biology in the University of Wales and later Principal of the Royal Agricultural College, Cirencester. He was educated at Westminster School and from there went up to Christ's College, Cambridge, with the Triplet Exhibition and an open exhibition in 1914. At Christ's he started reading medicine but after one term, he joined the 6th Battalion, the Rifle Brigade in December 1914 as a Second Lieutenant and served in France and at Salonika. He was seconded to the Royal Flying Corps in April 1917 as an observer and received his pilot's wings in Egypt. He returned to England in 1918 and was posted to the Central Flying School at Upavon, gained a 1A Certificate at the Advanced Flying School and completed his war service as an instructor. Demobilized in January 1919 he returned to Christ's gaining the BA degree in 1920. He went to St Bartholomew's Hospital in April 1920 and qualified with the Conjoint Diploma in 1923. Next year he passed the Cambridge BCh and in 1925 obtained his MB. He received the MD degree in 1933, having gained the Edinburgh FRCS in 1926 and the English Fellowship in 1929. In 1924 he was house surgeon at All Saints' Hospital for Genito-Urinary Diseases, where he later became registrar and assistant surgeon and was much influenced by Canny Ryall. He held appointments at the Royal Waterloo Hospital, the Bolingbroke Hospital, and at the King Edward VII Hospital for Officers, in each case as consultant in urology. In the second world war he was in the medical branch of the Royal Air Force with the rank of Wing Commander and was officer in charge of the surgical division at the RAF Hospital, Cosford. In his professional life he was Vice-President and an Honorary Fellow of the Royal Institute of Public Health and Hygiene, Secretary and President of the Hunterian Society, a member of the Council of the Royal Society of Medicine and Vice-President of the Section of Urology, and a founder member of the British Association of Urological Surgeons. He was a skilful instrumentalist and endoscopist and wrote many papers in specialist journals as well as his book *Essentials of urology* which was published in 1950. Ainsworth-Davis was an athlete of considerable distinction gaining his colours at Christ's at rugby, tennis and athletics. He won a gold medal in the 4 x 400 metres relay in the 1920 Olympic Games and in the same year represented the British Empire against the United States. As a boy he played the violin, and when Sir Adrian Boult brought the BBC Symphony Orchestra to an RAF station during the second world war and was told he was going to meet a Wing Commander Ainsworth-Davis he asked correctly, if this would be the same man who, as a boy, had taken the solo part in Mendelssohn's violin concerto at a Westminster School concert. Sir Adrian remembered the performance as a most distinguished one. At Christ's College he was a member of the 'Original Christie Minstrels' and during his student days at Bart's led a dance band. He was a devotee of ballroom dancing and for this also won a gold medal. He was an enthusiastic Freemason and ran a Lodge of Instruction for many years. Ainsworth-Davis was twice married: first in 1920 to Marguerite Wharry, sister of H M Wharry FRCS (1891-1933), by whom he had one son and two daughters; and secondly in 1947 to Irene Hope. He died on 3 January 1976.