Good job Nick (like the name too). I've never heard of this being looked at before. Unless you have your dyno goggles on (as Dave obviously did that day) you wouldn't look at is as a dyno. As soon as you do, it is bloody obvious.
As Nick says it's pure, good fun and quite tricky.
Ball park grade of 7a is fair but (in my opinion) it felt harder than Clubber Lang at Ilkley, which is 7a+. Like Nick said conditions will play a part in holding the break.
Nice snaps Dave