Born at Cardiff, South Wales on 7 August 1876, the son of John Jennings, timber merchant, and Mary Lawley, his wife. He was educated at Cardiff University and in Geneva, with the intention of entering his father's business. He quickly abandoned work in the office, entered St Bartholomew's Hospital and graduated at the University of London after taking honours at the BS examination. At St Bartholomew's Hospital he acted as intern in the midwifery department, then under Sir Francis Champneys, and afterwards became house surgeon to Sir Henry Butlin and William Bruce Clarke in 1901-02. For a short time he was demonstrator of pathology when Sir Frederick W Andrewes was head of the department, but soon left the hospital and entered private practice, first at Hampstead and afterwards at 13 John Street, Mayfair, where his social qualities and his absolute honesty of purpose endeared him to a wide circle of friends and patients. He was surgeon to the Western General Dispensary, and during the war of 1914-18 acted as surgical specialist to the Queen Alexandra Military Hospital and consulting physician to the Swedish War Hospital and to the Michil Hospital at Queen's Gate, where his fluent knowledge of French was of great assistance. He married Gwendolyn Thomas on 12 July 1906, but had no children. He died on 5 July 1934; subject to his wife's life interest, he left his whole estate to St Bartholomew's Hospital for the endowment of beds or the foundation of scholarships for medical students.