Percy Falconer was born on 14 October 1887 at Madras, India, the son of Doctor Samuel Ebenezer Falconer and Elizabeth Falconer. He was a Cadet in the Training Ship TS CONWAY at Liverpool from September 1903 to August 1905 and then, on 29 November 1905, he signed indentures to serve from 14 December 1905 to 24 June 1909 in the square-rigger Glenesslin.  He joined the RNR on 5 August 1905 as a Probationary Midshipman and, before being called up for war service, he had been Third Mate of the Inkosi of the Harrison-Rennie Line.

Sub Lieutenant Falconer started his RNR Training on 2 August 1914 and was appointed to the Submarine Depot Ship HMS MAIDSTONE at Harwich for HMS E10 as Navigating Officer, as an Acting Lieutenant, on 16 August 1914. E10 was sent to patrol off the North-North-West of Heligoland on 18 January 1915. The submarine parted company with its sister HMS E5 in the early evening of 18 January and was not seen again.

It is thought that E10 was mined on or about 18 January and was assumed to have been lost with all hands in this incident. The Commonwealth War Graves Commission records that the loss took place on 21 January 1915 which, it is assumed, is the day the submarine should have arrived back at Harwich.

Percy Falconer was married to Miss Ethel Violet, Mary Goodman in St Pauls Church, Hammersmith on 22 September 1914.

Percy Falconer had the dubious distinction of being the first Royal Naval Reserve submarine officer to be killed in action in the First World War. He is commemorated on the Portsmouth Naval War Memorial on Panel No. 7.