Leslie Edward Buckler was born in Devonport, Devon, on 1 March 1905, the son of Thomas John Baker and Emily Lavinia Buckler. He joined the Royal Navy as an Engine Room Artificer Apprentice on 16 August 1920. Having completed his apprenticeship, he served in the cruiser HMS CARADOC, the battle cruiser HMS HOOD and the cruisers HMS FROBISHER, HMS NORFOLK, HMS CARLISLE, and HMS GREENWICH, by which time he had been advanced to Chief Engine Room Artificer Second Class. He was then promoted to Warrant Engineer on 1 January 1938.

On 6 August 1938, he was appointed to the Submarine Depot Ship HMS MEDWAY, and, on 17 January 1939, he was appointed to HMS GRAMPUS as Engineering Officer. GRAMPUS conducted three war patrols from Singapore in the Sunda Straits, off Sabang and off the West coast of Sumata. GRAMPUS was then redeployed to the Mediterranean, arriving at Malta on 13 May 1940. Having successfully laid a minefield between the Sicilian ports of Augusta and Syracuse, HMS GRAMPUS was, on 16 June 1940, detected by Italian anti-submarine vessels, attacked, and was sunk with all hands.

Leslie Buckler was the husband of Agnes Adair Buckler. He is commemorated on the Portsmouth Naval Memorial on Panel No. 37 Column No. 2.