Hector McGregor was born in New Zealand. After joining the RAF in 1928 he served as a pilot but in 1931 he attended the Aircraft Engineering Course and he subsequently undertook several engineering-related tours. In 1959 he was appointed Commander-in-Chief of Fighter Command and in 1962 he became Commander-in-Chief of the Far East Air Force.
Following his retirement from the RAF, McGregor became Chairman of the New Zealand News Consultative Board in 1964.