My thanks, Bubbers44 - not trying to be "right"... heaven knows there are enough theories floating about to fill a tanker, but wishing to have the argument at least countered so it can be dismissed, pondered, etc.
My point was, if the aircraft was essentially level, there would be no increase in indicated airspeed as a result of any blockage. By all indications we have access to, the pitch-up occurred from level flight. It is true that the airspeed may have increased as altitude increased by the former was not the instigating "cause" because the airspeed required the increase in altitude to increase in indication.
It was asked on a previous page, why TOGA if it was an overspeed?
But as just about everyone here now has pondered/asked/puzzled...why pitch-up just for an unreliable airspeed?
I suspect the Stall warning was a result of aggressive pitch up, not a cause for the PF to pull up but as it got worse, the PF (essentially) pulled more, and longer. It isn't the first time a stall warning has been associated with a hard pull on the control column.
Perhaps too, the upcoming BEA 3rd Interim will cover this and many other questions now on the board.
BTW, I have seen significantly different (lower) Mach numbers in the calculation done by DJ77, (more along the lines of the first ones he did) so perhaps confirmation of how the result was derived might be in order. I'm not qualified to do the math but the question needs to be asked. As expressed in an earlier post, I've had an increasing airspeed in climb (B767) and while it reached the overspeed limit it took much more altitude than 3000ft (FL250 > FL280 approx) to do it. Now it's thicker air and the drain may have only been partially blocked reducing the rate of increase.... ;-7