Denis Rebbeck followed his father Sir Frederick Rebbeck as Chief Executive of Harland & Wolff. He was born in Belfast and educated at Campbell College. He then studied at Pembroke College, Cambridge, where he was keen on the mainstream sports there of rowing and Rugby. On graduating in 1935 with a BA in Mechanical Sciences, he joined Harland & Wolff, where he was to remain for the rest of his career, although his first work was building marine diesel engines under licence for Burmeister & Wain, in Belfast. His father was already Chief Executive and the firm was heavily engaged in war production; Denis's responsibility was the production of heavy gun barrels. In 1946 he became a Director at Harland & Wolff, in 1953 he was appointed Deputy Managing Director and eventually, on his father's retirement Managing Director, 1962.