Leslie Westall was born in Burnley and lived in South West London. He enlisted in the Royal Corps of Signals and volunteered for Airborne forces. 

Leslie, with the rank of Cpl. was parachute jump trained at RAF Ringway on Course 35. This course ran between 29 October and 7 November 1942. This course report states that Leslie injured his knee on his second practise jump from a training balloon and did not therefore complete any training jumps from aircraft. The course report also notes that there were 2 fatalities, Gnr Laigmaid and L/Cpl Staley. 

Lance Sergeant Westall was posted to J Section, attached to 2nd Battalion the Parachute Regiment, 1st (Airborne) Divisional Signals, Royal Corps of Signals, and took part in Operation Market Garden (Arnhem).

L/Sgt Westall is known to have been killed operating his radio set in a house on Eusebiusbinnensingel, near the Rhine Bridge at Arnhem (Roll of Honour, 5th edition, 2011), on 19 September 1944, aged 24, and is commemorated on the Groesbeek Memorial to the missing.