Rooke was born in New Cross, London, the younger son of F. G. Rooke. He attended Westminster City School and Addey and Stanhope School before studying Mechanical Engineering and Chemical Engineering at University College London, then served in REME until 1949, attaining the rank of Major. He married Brenda Evans in 1949, and they had a daughter, Diana, who survived him. He died 2 September 2008. Lady Rooke died in 2017.
From 1949 he worked in the gas industry, first on coal tar, then on Liquefied natural gas (LNG), pioneering the sea transport of LNG. He was aboard the ship making the first delivery of LNG to the UK in 1959.
He became Deputy Chairman of the Gas Council in 1972, and along with the Chairman, Sir Henry Jones. and Sir Arthur Hetherington, he was responsible for combining the Gas Council and 12 separate gas boards into the British Gas Corporation in 1973.
- Historic Gas Times (Dec 2008) issue 57 ISSN 1475-617X Sir Denis Rooke, A Tribute
- The Telegraph says Elizabeth, others say Brenda
- The Chemical Engineer issue 808 October 2008 page 66
- The Guardian 8 September 2008 Sir Denis Rooke
- The Independent 8 September 2008 Sir Denis Rooke
- news@lobro issue 27, April 2004
- "Honorary Graduates 1989 to present". bath.ac.uk. University of Bath. Retrieved 18 February 2012.