Wensleydale, this has been mentioned on here before, but in a slightly different and may I say, more credible vein. Freeman Dyson ,who was a young operational research scientist, came up with the idea of removing the turrets to give the Lanc an increase of 50mph. This was during the winter of 43-4 during the Battle of Berlin. He said that his boss was a career civil servant, who was not prepared to tell Harris. I believe it was also not proceeded with as it would have affected production and having turrets was good for morale, in that it gave aircrew comfort in being able to fight back.