John Michael Alfred Sly was born on 22 March 1931. He attended the Colonial Service Course at Cambridge University, October 1953 - July 1954, and the Imperial College of Tropical Agriculture, Trinidad, September 1954 - July 1955. Thereafter, he worked as an agronomist for the West African Institute for Oil Palm Research, 1955-1966, from which he retired as Deputy Director. Sly's work took him to places throughout Nigeria and to other countries in West Africa. He became a biometrician at M.A.F.F. Plant Pathology Laboratory, Hatching Green, Harpenden, in 1966, where he was leader of the Pesticides Survey Group, designing surveys of the use of pesticides in agriculture and analysing the results. He took early retirement in 1986. John Sly's father, Alfred Gordon Edward Sly (1897-1974), was born on 25 January 1897. He attended King Edward VI Grammar School, Southampton, 1909-1912, and became an engraver with the Ordnance Survey. He joined the Territorial Army in 1914, then enlisted in the 5th Hampshire Regiment. Sly spent the war in India, Palestine and Egypt before rejoining the Ordnance Survey at Southampton in 1919. In 1920 he joined the Colonial Service as a surveyor in the Land and Survey Department of the Gambia, where his main task was marking out the international boundary with Senegal. He married Doris Evelyn Millard (1900-1999) in 1924, and was transferred to Nigeria in 1927. He was forced to retire after his post was removed in 1931, and lived in West Norwood until he rejoined the Ordnance Survey as a draughtsman in 1934. Sly worked at Southampton before moving to Chessington in 1943, and was promoted successively before retiring in 1964. During the Second World War he was a Fire Officer at the Ordnance Survey, and was trained to work with poison gas. He died on 17 August 1974.