Pete,
Thank you for the 'gen' on the Air Bomber. Even at that early stage we were being influenced by the US terminology ("Bombardier" is their name for him). I'm slightly amused by "...If attacked by enemy aircraft he manned a gun, usually in the forward turret...." And how long would that take ? (from the Nav station behind the pilot right forward into the Nose ?).
They seem to have been thinking of daylight raids like those of the 8th Air Force B-17 formations, which were often under sustained attack from fighters, whereas at night our "heavies" had to contend with sudden attack from a night fighter, which might last only for a few seconds. He'd hardly have time to get his head out of the astrodome before it was all over (one way or another).
I think it more likely that he would have a "roving commission" to rest the other two gunners (for it must have been impossible to keep up an intense lookout hour after hour without a break). But what am I theorising for ? There are people on this Thread who were there. Let's hear from them - or from their writings.
Cheers, Danny.