Rear Admiral Peter Gerald Hammersley CB OBE (nicknamed Spam; 18 May 1928 – 16 January 2020) was an English Royal Navy officer who served from 1946 to 1982.

Hammersley won a scholarship to Britannia Royal Naval College to train as a deck officer but his eyesight was too poor.

In 1960 he became the first marine engineering officer to serve aboard the Royal Navy's first nuclear-powered submarine, HMS Dreadnought.

Hammersley helped design the Swiftsure-class of submarines and commanded a number of shore installations including the Royal Naval Engineering College.

He served as aide-de-camp to Queen Elizabeth II and was Chief Staff Officer Engineering for the fleet in the 1982 Falklands War.

[nb 1][5][6] He served aboard the light cruiser Liverpool from 1950 until he was posted to the advanced marine engineering course at Royal Naval College, Greenwich in 1951.

[2] Upon completion of the course he joined the aircraft carrier Ocean and served on active duty during the final year of the Korean War (1950–1953).

One of those chosen was Hammersley who, in 1957, was summoned from Imperial College London, where he was studying for a diploma in nuclear engineering, to meet with Mountbatten and Rickover.

[1][4] Hammersley was promoted to lieutenant commander on 26 September 1958 and afterwards served aboard the USS Skipjack, commissioned in April 1959, under Commander (later Vice Admiral) W. W. Behrens Jr.[nb 2][4][7] Rickover's orders prohibited British officers from standing watches unsupervised and stipulated that they must arrive in the US unaccompanied by their families.

[4] During this time, Rickover approved the provision of technical support and the supply of a Skipjack-type nuclear propulsion system to the British under the 1958 US–UK Mutual Defence Agreement.

[1] Hammersley was appointed aide-de-camp to Queen Elizabeth II on 7 January 1980, serving until 7 July 1980 when he was promoted to rear admiral.

[13] He served as chief executive officer of the Internal Combustion Engine Manufacturers' Association from 1982 to 1985 and as director of the British Marine Equipment Council from 1985 to 1992.