Born at Norwood on February 19th, 1864, the son of Frederick Henry Leaf, of Burlington Lodge, Streatham Common, Surrey, and was educated at Marlborough, at Trinity College, Cambridge, which he entered in 1882, and at the London Hospital, where he was House Surgeon, House Physician, and later on, Demonstrator of Anatomy. In 1899 he was appointed Assistant Surgeon to the Cancer Hospital and to the Gordon Hospital for Diseases of the Rectum. He remained actively connected with both institutions for the eleven years preceding his death. He became full Surgeon at the Gordon Hospital in 1904 and to the Cancer Hospital in 1905. Leaf's personality was one of great charm. At the London he had been affectionately known as 'Daddy Leaf', and throughout life he evinced a fine generosity of spirit and was popular with his colleagues, one of whom, at the time of his death, notes that he had the characteristics of a visionary and idealist, and that they meet with a poor return in a strenuous professional life. He was a fine athlete, was in the Gymnasium Eight and the Cricket Eleven at Marlborough, and in after-life excelled as a racket player. In 1908 he won the singles racket handicap at Queen's Club, starting from scratch, and had been in 1906 and 1907 in the semi-final ties with one of his brothers for the Amateur Doubles Championship. He was a Captain in the London Division of the RAMC (Electrical Engineers). He practised at 75 Wimpole Street. At one time he was Clinical Ophthalmic Assistant at Moorfields and at the London Hospital, and Clinical Assistant at Golden Square Hospital. He died of cancer at Eastbourne, after a long and painful illness, on October 5th, 1910. He was survived by Mrs Leaf, his devoted nurse, and by his daughter. Publications:- *Surgical Case Book Charts for Rectal Diseases*, London. *The Surgical Anatomy of the Lymphatic Glands*, 8vo, coloured plates, London, 1898. *The Clinical Causes of Cancer of the Breast and its Prevention, with Analysis of a Hundred Cases*, 8vo, London, 1904. *Lancet Experiments with Chloroform*, 1903, of which he was joint-author. He edited and made a translation of Delamere, Poirier, and Cunéo's *The Lymphatics*, 8vo, 117 illustrations, London, 1903. "New Treatment for Inoperable Cancer of the Breast." - *Edin Med Jour*, 1901, NS ix, 452. *Cancer of the Breast Clinically Considered*, 8vo, plates, London, 1912. He was also sub-editor for Rectal Diseases to the *Med Times and Hosp Gaz*; and in the *Lancet*, 1910, i, 440, described "An Illuminating Mouth-Gag", accompanying his note with an illustration.