James (Jamie) Hamilton was born in Indianapolis, Indiana, 15 November 1900, son of James Nelson Hamilton and Alice van Valkenburg, and moved to Scotland at the age of five at his father's bidding. He was married twice, firstly to Jean Forbes-Robertson (daughter of actor-manager Sir Johnston Forbes-Robertson) in 1929, though the marriage ended in 1933, and then to Countess Yvonne Pallavicino of Rome in 1940, with whom he had one son, Alastair. He was educated at Rugby School and Caius College, Cambridge, where he excelled at rowing, going on to win the Olympic Eights Silver medal at the Amsterdam games in 1928. He remained a keen and active sportsman throughout his life, taking up golf in middle age after a youth of skiing, hiking, rowing and recreational piloting. After graduating from Cambridge in 1922, he travelled extensively throughout the United States, where he began to build up a web of contacts in publishing that would stand him in good stead for the rest of his life.
In 1924 he joined Jonathan Cape before becoming the London Manager for Harper & Brothers in 1926, eventually rising to found Hamish Hamilton, Ltd., in 1931. During World War II, he served in the Army in Holland and France, evacuating in 1940 before being seconded to the American Division of the Ministry of Information in 1941. A daredevil pilot, diver and skier, Hamish Hamilton had a famously low threshold of boredom, despising committees and meetings, even though he was Honorary Secretary of the Kinsmen Trust from 1942 until 1956 and a governor of the London Old Vic from 1945 to 1975. It is thought his refusal to sit on boards such as the Publishers' Association was responsible for keeping him from receiving a Knighthood, though he was made a Chevalier of the Legion of Honour in 1953 and a Grande Officiale of Italy's Order of Merit in 1976. He died in London in October, 1988.