Sydney was born on 25 April 1920 in Cheetham, Manchester to Simion and Emily nee Hartley. In 1939, the family were living at 143 Broadway, Manchester where Sydney worked as a painter and decorator. Sydney’s older brothers, Harry worked as a waterproof garment cutter and Louis was a salesman of cleaning powders.

Sydney was the wireless operator/air gunner on Wellington BK341 which departed RAF Mildenhall on a night operation to mine in the Kattegat area. The aircraft was hit by flak at 23:29 hours and crashed into Ho Bay approximately one kilometre east of Skalling Ende killing all onboard.

Pilot, Sgt Charles John Shalfoon, RNZAF, NZ413897 age 22.
Obs, Sgt Harold Wolfenden, 1237318 age 32. Buried Esbjerg (Fourfelt) Cemetery Denmark.
W/Op, Sgt Algernon Parsons, 1196149, age 22. Buried Esbjerg (Fourfelt) Cemetery Denmark.
Sgt Sydney Posner, 1078313
R/G, Sgt Roy Harold Scott, RCAF, R.137578, age 20. Buried Esbjerg (Fourfelt) Cemetery Denmark.