I bet he'll remember the dreaded main spar. It goes right through the fuselage. Gives the Lanc huge strength, but you have to crawl over it. I have a picture in one of my Lancaster books of someone doing just that.
It says that many a shin lost an argument there - and that's with the plane sitting on the concrete, so trying to climb over that when the Lanc is in a death dive is just not going to happen. If the aircraft recieved at direct hit by flak, there was little chance of anyone surviving, save perhaps the pilot if he was wearing a seat-type chute, which was standard issue by 1944, and later extended to rear gunners.
Just a bit of trivia, the Lanc was a bit erratic where heating arrangements were concerned. All the hotness from the engines was piped out round the wireless op's position, so, coupled with the warmth from the set, he sweltered - even at high altitude. On the other hand, it was brass monkey time for the poor rear gunner, and, although he had a hot air hose, it got so cold back there, that many would put it up their trouser leg - hey, it's not as if you can be seen by anyone, and you gotta protect those fundamentals!