Admiral of the Fleet Sir Caspar John GCB (22 March 1903 – 11 July 1984) was a senior Royal Navy officer who served as First Sea Lord from 1960 to 1963.

[4] There he won the prize for the best gentleman in the school and a copy of Jane's Fighting Ships, and it was this, together with a wish to seek a more orderly existence, that inspired him to join the Royal Navy.

[10] It was at this time that the future of naval aviation was being debated; the issue caught his imagination and during his qualifying exams at the RAF Flying Training School at Netheravon in 1925 (he gained first class certificates in gunnery and torpedo), he applied to train as a pilot in the Fleet Air Arm, then under the dual administration of the navy and Royal Air Force.

[9] In December 1926, John joined the aircraft carrier HMS Hermes for flying duties on the China station during the conflict between the communists and Chiang Kai-shek's nationalist armies.

[7] On returning from China he bought his own aeroplane, an open cockpit Avro Avian and took part in three Royal Aero Club King's Cup Races.

[14] There he arranged the training of British pilots in Canada and the US and met the Russian aircraft designer Igor Sikorsky, with whom he discussed the introduction of helicopters for the Royal Navy after the War.

[14] After attending the Imperial Defence College in 1947, John was given command of the Royal Naval Air Station Lossiemouth in January 1948.

[14] Appointed a Companion of the Order of the Bath in the 1952 Birthday Honours,[18] he was posted to the Ministry of Supply as Deputy Controller of Aircraft that year and, having been promoted to vice admiral on 30 March 1954,[19] he became Flag Officer, Air (Home) at Lee-on-Solent in June 1955.

[14] He was advanced to Knight Commander of the Order of the Bath in the 1956 Birthday Honours,[20] promoted to full admiral on 10 January 1957, and became Vice Chief of the Naval Staff in May 1957.