Dave Reid -- Yup, I'd read that but there is something odd here. The GoPro was stated earlier in the report to have had a partly-obscured view of the ASI.
In Appendix H (5) page 301 of the report it is stated:
Discussion of airspeeds in this report are based upon the values assumed at the time of the data gathering flying.
This begs the question what did the needle show during the manoeuvre and what was the actual airspeed? I suspect that the speeds have been correlated to the videos and are probably a matter of fact. However the pilot might have been misled and of course would have been relying on his primary ASI.
Perhaps I'm being dense or missing something. I probably am, it's hardly likely the AAIB would make such an assumption unless they were certain. However, as an engineer I automatically feel uneasy when people make assumptions.