Thanks for the morning greeting Chris...actually it's 9:30pm where I am....hehehe
Sorry cannot help with the technical of the stall protection system. I've forgotten or, more likely, I never knew! but I do recall it was advanced at the time
However, I was the VC10 Sim F/E senior instructor for 3 years and I do recall introducing the stall system to converting crews . We would ask the trainee pilots to purposely stall the sim and recover. Some pilots really put themselves into the training and I can say that the stick-push was frighteningly fierce. Our training consisted that they should make every effort to prevent it becoming active. I think they got the message!
In all my flights on the 10 I only heard the shaker once, when my Captain, showing off to dignitaries, did a max thrust/V2 climb...but it only blurped for a second or two. That was probably that phase advance you talk about as we were nowhere near stalling..we were accelerating and climbing at an astonishing rate.
I seem to remember discussing...maybe we should de-activate the stall warning C/B for air shows, but that went nowhere.