No 1 Group Gas patch

As far as I am aware, no other bomber group throughout the war carried the circular gas detection on its aircraft.

The thing I would like to know is . . . Does anybody have concrete evidence as to why, and more importantly, When they were introduced ??

I have photos that date them to late 1943 which in itself is quite late in the air-war but they were still seen on new issue aircraft in 1945.
If anybody knows of any No1 Group Bomber Command directive that can resolve this I would be grateful.

rgds
Ian