David Waldron Smithers was born on 17 January 1908 in Knockholt, Kent, the home of his father Sir Waldron Smithers JP, stockbroker and staunchly Conservative MP, and of his grandfather Sir Alfred Smithers MP, chairman of the Canadian Grand Trunk Railway. A knighthood was clearly an obligatory achievement for David and was most richly deserved when it came. Charterhouse, Clare College Cambridge and St Thomas's provided his education. He qualified in 1933 and in the same year married Gladys Margaret Angel, by whom he was to have a son, Andrew, now a merchant banker, and a daughter, Elizabeth, now married to a major general. After sampling several specialties in junior appointments he settled on radiotherapy, although at the time this also required considerable experience in diagnostic radiology. He was appointed director of the radiotherapy department at the Royal Marsden in 1943 and Professor of Radiotherapy in the Institute of Cancer Research in 1946. With the ready co-operation of the surgeons he transformed the work of his department and the general policy of the Royal Marsden, making it a leading centre for the treatment of cancer not only by external irradiation but also by the use of implanted radio isotopes. He acknowledged as his particular guides on the surgical side Cecil Joll and Laurence Abel, as well as Sir Clement Price Thomas at the Brompton, where he was also a consultant. In his turn he exercised enormous influence over the younger generation of surgeons, particularly the urologists. As Chairman of the Faculty of Radiology from 1958 to 1961 he was a co-opted member of the Council of the Royal College of Surgeons and was elected a Fellow in 1963. Besides working for the advancement of his specialty he gave stalwart service to many NHS bodies, as a member of the Central Health Services Council, the Standing Medical Advisory Committee and the Cancer Advisory Sub-Committee. He was knighted in 1969 and also received widespread international recognition. He was made a Knight Commander of the Sovereign Military Order of Malta. With all this he remained the most friendly and approachable of men and settled to a serene retirement cultivating remarkable roses in a garden of his own creation, while writing a stylish but light-hearted biography of Jane Austen, a volume of reminiscences and an amusing account of doctors who were also writers. He died peacefully at home on 20 July 1995, survived by his children.