after reading a bit about IFF it seems to me that in 1943 bombers of Bomber Command had the system on board and chain home radar stations have sent pulses and received pulses back from the aircraft.

Can anybody tell me if in 1943 the a/c also used the system to identify other a/c? In other words, did the a/c send the interrogator pulse to identify other a/c or did only chain home staions (and maybe ships) do this?