Sidney was born in 1920 in Chorlton, Lancashire to Lewis Cornofsky and Esther nee Raff and was the eldest of three siblings, Vera and Beina. Their father Lewis changed his name from Cornofsky to Kirk and ran a boot and shoe factory in Manchester.

Sidney was the observer on Blenheim EH318 which departed RAF Oulmene, Algeria to attack communications and transport in the area west of Sousse. The aircraft crashed on takeoff killing Sidney and the other two crew members:
Canadian Pilot, James Anderson Mayne, R/86852
New Zealand W/Op, Leslie John O’Neill, 411095