Vice-Admiral Sir Ian Lachlan Mackay McGeoch, KCB, DSO, DSC (26 March 1914 – 12 August 2007) was a commissioned officer in the Royal Navy of the United Kingdom.

A burly figure, he was educated at Pangbourne Nautical College, and joined the Royal Navy in 1931 as a special entry cadet.

[1] McGeoch took command of HMS Ursula on one patrol, but was not confident in his own abilities, so, unusually, elected to return to England to take the "perisher" a second time.

[1] He and his brand new ship (named HMS Splendid January 1943) were posted to Gibraltar to take part in Operation Torch,[1] and then back to Malta.

From November 1942 to May 1943 (the Operation Torch landings to the defeat of Axis forces in North Africa), Splendid sank more tonnage on its six patrols than any other submarine.

[1] Three accurately-dropped patterns of depth charges forced Splendid to the surface, where McGeoch ordered the crew to abandon ship and scuttled the vessel.

[1] After the surrender of Fascist Italy in September 1943, he was able to walk out of the camp gate and travelled 400 miles (600 km) to Switzerland, where a metal fragment was removed from his sightless right eye.

Promoted to lieutenant commander, he became Staff Officer (Operations) for the 4th Cruiser Squadron in the British Pacific Fleet in the run up to the surrender of Japan on 2 September 1945.

[1] After helping to repatriate British prisoners of war, he returned to the United Kingdom in 1946 to take command of the Hunt-class destroyer HMS Fernie.

[1] He studied social sciences at the University of Edinburgh from 1970, and received an MPhil in 1975[1] after the direction of historian Professor John Erickson, writing a thesis on the origins, procurement and effect of the Polaris programme.

[1] He worked with other senior officers, including General Sir John Hackett, on The Third World War: The Untold Story (1978 and 1982).