Frank Lockwood Larkins was the twin brother of Brian Lockwood Larkins. The twins were born to Margaret and Walter Larkins on 20 March 1899. They had four sisters, but these are un-named in records. Frank Larkins left school at the age of thirteen to attend the new Royal Australian Naval College at Jervis Bay, NSW, and was part of its first intake in 1912. He finished his course successfully in December 1916, when he would have been seventeen.

Frank Larkins was an outstanding cadet, as a paragraph in The Age, 20/1/1917,p.8 testified: 

Midshipman Frank Lockwood Larkins, R.A.N., son of Mr. and Mrs. Walter Larkins, of East Melbourne, has sailed for England to join the Grand Fleet in the North Sea. He was educated at the Melbourne Church of England Grammar School, and from there went to the R.A.N.College.

He was appointed first cadet captain of the college, and afterwards was senior chief cadet captain. He was captain of the cricket, football, and tennis teams, and also had his colours for athletics. He is a cousin of the late Sir FrankLockwood, K.C., England.

In January, 1917, Frank Lockwood  proceeded to the North Sea where he served first on HMS Royal Sovereignty and then on HMS Vampire. From the Vampire he was moved to Portsmouth, to take part in a convoy led by HMAS Platypus, built at Portsmouth as a submarine depot ship for the Australian Navy. The Platypus was launched and was to lead a convoy of submarines back to Sydney, via the Suez Canal.

Frank Larkins was appointed to submarine J2 as a Sub-Lieutenant. Although the convoy arrived safely at Sydney on 15 July 1919, Frank Larkins had been lost overboard at sea on 20 June 1919 in the Karimata Straits, off the west coast of Borneo. A twelve hour search of the surrounding waters failed to find him. He was twenty years old. His name is recorded at the Australian War Museum's Roll of Honour (R1714609).

The Sydney Morning Herald, 24 June 1919, P.8 reported his death:

LOST OVERBOARD. SUB-LIEUT. LARKINS OF SUBMARINE J2., MELBOURNE, Monday.

The Navy Department announces with regret that news has been received from H.M.A.S. Platypus, submarine depot ship that Sub-Lieut. Frank Lockwood Larkins, R.A.N., was lost overboard from submarine J2 on June 20 in Carimata Strait, on the westcoast of Borneo. This young officer was a Victorian.

Frank Lockwood Larkins' name is recorded at the Australian War Museum's Roll of Honour (R1714609).