John Charles Nicholson was born at Chilworth, Surrey, on 10 January 1904, the son of Sir Charles Archibald Nicholson, the church architect, from whom he inherited the baronetcy in 1949, and the grandson of Sir Charles Nicholson, DCL, LLD, MD, one of the founders of Sydney University and its first Chancellor. He was educated at Brighton College and New College, Oxford, before entering St Bartholomew's Hospital for his clinical studies. He won the Willet Medal for operative surgery in 1929 and qualified in the same year. His early appointments were as house surgeon to the Prince of Wales Hospital, Tottenham, and to St Bartholomew's Hospital. He was later demonstrator in physiology and pharmacology at St Bartholomew's and surgical registrar to the London Lock Hospital, the National Temperance Hospital and the Royal National Orthopaedic Hospital. In 1932 he joined the Territorial Army and he passed the FRCS in 1934. Throughout the war he served in the Royal Army Medical Corps as a surgical specialist with the rank of Lieutenant-Colonel and after demobilisation was awarded the Territorial Decoration and appointed Honorary Lieutenant-Colonel. He went to the United States after the war and was Fellow in Surgery at Harvard University from 1947 to 1948. On his return he was surgeon to Bethnal Green, St Leonard's and St Matthew's Hospitals in the East London Group from 1950 until his retirement in 1969. He was a regular attender at postgraduate meetings and retained an active interest in surgery all his life. He married Dr Caroline MacNeice, a medical practitioner, in 1928. She was the daughter of the Right Reverend John Frederick MacNeice, Bishop of Down, Connor and Dramore, and a sister of the poet Louis MacNeice. There were no children of the marriage. His wife died tragically in a car accident in 1981. After retiring he lived at Sunbury-on-Thames and enjoyed his hobby of sailing. He died on 16 March 1986, aged 82.