Greg Yup, makes perfect sense that the Sabre was in the running. It weighed slightly less than the Vulture and put out more power. I guess it depends when they were looking at the Sabre. Things weren't looking all that rosy for the Napier in 1938. A pity that Bristol's sleeve value-making approach didn't get pulled in sooner.
Jon Interesting. I got the built-but-not-flown from Green & Swanborough (WW2 Fact File RAF Bombers Part 2). It didn't really make sense though. I know the Centaurus got pushed to the back-burner so Bristol could focus on the Hercules. Still, with the Vulture mess at hand, why would they finish the Centaurus conversion and then not even bother to fly it?