Nobody's mentioned it, so I suppose I must. Fighter affiliation exercises were more for training the bomber gunners, rather than the fighter pilot. In such exercises the fighter pilot wasn't receiving return fire, so he wouldn't be in a position to judge how well the manouvre was succeeding in engaging him.
The Lancaster - and other 'heavies' - didn't simply use the corkscrew as an evasive manouvre. It was initiated by the gunners and gave them a better shot at an attacking fighter than the fighter had at them. It would generally be the gunner who spotted the approaching fighter who gave the "Corkscrew left (or right)" instruction to the pilot and who would engage the other aircraft knowing in advance which way the turns would be going.