http://www.bbm.org.uk/airmen/Gillies...rkin-PB-Ap.jpg
This a picture of 91 Squadron sometime in 1941. The pilot on the extreme right is identified as Appleford? but he looks very like FO "Chris" Le Roux to me. Le Roux joined 91 Squadron on 20 February 1941. The pilot second from left is identified as Flt Billy Drake.
My confusion is that Drake, who led A Flight had left 91 Squadron on 11 February 1941 and that the other pilots in the picture, Sergeants Gillies and Perkin and FO Barthropp are members of B Flight, as was LeRoux.
Also, and perhaps crucially, the pilot identified as Drake appears to have sergeant's stripes on his sleeve.
regards
Keith