Anyone flying a twin engined aircraft, in the dark inside the bomber stream is asking for trouble.
If that is the case it must have been tough on the Wellington guys. Admittedly Lancs would probably be higher, but they could well be in among the Stirlings while these were still on Ops. Presumably this point would be covered at briefing when Wellingtons were involved on an Op, but on the "shoot first, ask questions later" principle some of them must have been friendly fire victims