Born on 6 July 1871 elder son of W H Smith, a civil engineer at Chatham Naval dockyard, P M Smith was educated at Epsom College, as were his brother Sidney Maynard Smith FRCS, surgeon to St Mary's 1906-28, and son and at St Mary's. While practising as a children's physician he gained the Fellowship in 1909, but never took up surgery. He was clinical assistant to the Victoria Hospital for Children, and subsequently physician to the Kensington Hospital for Children and from 1928 to 1952 to the Princess Louise Children's Hospital. He served on the Council of the Medical Society of London, and was an active member of the distribution committee of the Royal Medical Benevolent Fund until his ninetieth year. In Freemasonry he attained the rank of Past Grand Deacon. Mrs Montague Smith died in 1953 and he died on 31 August 1961 aged 90, survived by his son Harold Montague-Smith a marine engineer.