I believe they were phased out of service (no new issues) before the end of the war.
They were replaced for a variety of reasons, they were expensive and increasingly so, they were bulky, and newer cloth jackets and trousers, coupled with electrically heated underwear, began to out perform them, with less weight and bulk, making them more comfortable.
Pictures I have seen of RAF fight crews of the 1950's seem to wear some form of cloth jacket similar to the US B-10 or B-15 jackets (worn with matching trousers, also very similar to USAF A-11).