Herbert Cooper-Key was born in Chelsea in 1888, the son of Astley Cooper-Key and Lady Evelyn Dundas Cooper-Key (nee Bartolucci).

He joined the Royal Navy as a Cadet at HMS BRITANNIA on 15 September 1903 and he was promoted to Midshipman on 15 April 1905 and to Sub Lieutenant on 15 June 1908.

He was appointed to the Submarine Depot Ship HMS MERCURY at Portsmouth for Submarine Training on 1 May 1909. On completion of Training, he was appointed to the Submarine Depot Ship HMS FORTH at Devonport for Submarines on 4 January 1910 and in continuation on his promotion to Lieutenant on 31 December 1910.

He was serving in the Submarine Tender HMS ONYX at Devonport ‘for Submarines’ when he died on 26 June 1912 in the Civil Hospital at Dover, from a cerebral haemorrhage following a fall from a motor cycle.