Several years ago I had occasion to talk to a gentleman, a retired Flt Lt Lancaster pilot, who described his nearly completed two tours of ops. He showed me his log book and I noticed several sorties to Berlin. He said he'd done more than that, and to other targets too, as he often flew with newly arrived captains, but didn't log them as he was only in an advisory role and not part of the constituted crew. His DFC was well earned.