Martin John Gilbert was born on the 25 October 1936, the son of Peter and Miriam Gilbert. He was educated at Highgate School then Magdalen College, Oxford. In 1963 he married his first wife, Helen Constance Robinson, with whom he had one daughter. He had two sons with his second wife Susan Sacher, and in 2005 married his third wife, Esther Poznansky.

Gilbert carried out his Army National Service from 1955-1957 before becoming a Senior Research Scholar at St Antony’s College, Oxford (1960-62). He worked as a research assistant to Winston Churchill's son, Randolph S. Churchill, from 1962-67 on the first volumes of the Official Biography of Sir Winston Churchill and, after Randolph's death, became the Official Biographer of Sir Winston's life in 1968.

Gilbert published numerous works including the multi-volume official biography of Sir Winston Churchill. Many of these works are about Churchill and a complete list of publications can be found in Sir Martin's entry in "Who's Who" (A & C Black). He died on 3 February 2015.