Leslie was born on 12 January 1922 in Islington to Isadore and Sarah née Walters and had a younger brother Aubrey. Their father Isadore worked as a travelling hosiery merchant and the family changed their surname from Israel to Walters. Leslie was privately educated at Haberdashers School and then attended Hornsey Art School, and was a commercial artist before he enlisted. During training at Falcon Fields in Arizona he met Tony Rosen and Lionel Anderson who also have a memorial page. Leslie was killed the same date as Tony Rosen, 18 November 1943.

Leslie was the pilot of Halifax DK244 which departed from RAF Feltwell at 17.45 on a Special Signals Duty to the Ludwigshafen area. The aircraft was recalled at 18.32 and overshot the runway striking a tree and crashing 20.20 at Black Dyke near Rockwold-cum- Wilton, two miles SSE of Feltwell, Norfolk but within the airfield perimeter. Leslie and the flight engineer Frank Bramall were killed instantly, and three other crew succumbed to their injuries.

Pilot, Leslie Israel
F/E, Frank Bramall, 1684804.
Nav, Thomas Nicoll, 161716, injured, died 19 Nov 43.
A/B, James Thomas McCormick Kean, 162520, injured, died 28 Nov 43.
Nav, Peter John Elldred, 117133. W/Op A/G, William John Mitchell Templeton, 656607, injured, died 21 Nov 43.
Sgt T.W. Brandon – injured
F/O D.B. Gaunt – injured