Brewsters second link gives this interesting paragraph,I could never understand why this was never even trialled on a small scale with Lancs and Stirlings...
Smeed and I agreed that Bomber Command could substantially reduce losses by ripping out two gun turrets, with all their associated hardware, from each bomber and reducing each crew from seven to five. The gun turrets were costly in aerodynamic drag as well as in weight. The turretless bombers would have flown 50 miles an hour faster and would have spent much less time over Germany. The evidence that experience did not reduce losses confirmed our opinion that the turrets were useless. The turrets did not save bombers, because the gunners rarely saw the fighters that killed them. But our proposal to rip out the turrets went against the official mythology of the gallant gunners defending their crewmates. Dickins never had the courage to push the issue seriously in his conversations with Harris. If he had, Harris might even have listened, and thousands of crewmen
might have been saved.
The extra speed would have made Lancs much more difficult to intercept as most enemy night fighters were fitted with draggy radar aerials and performance suffered accordingly