Thank you for coming back so promptly bast0n, and apologies BOAC for jumping in on a post directed to you. I will attempt to jump out of the way again ASAP!
If there is no evidence can we not surmise that nothing happened?
Brief answer, bast0n, no! No surmising at all would be a very good rule of thumb to adhere to anyway in Aircraft Accident Investigations, but certainly where you are constrained by regulation to be right "beyond all doubt whatsoever". Sorry, I know your attitude to the latter, but neither you nor I (nor W&D!) decide these things, the Air Board does it seems, and did!