Hughes500 I think if you ever had the chance to fly with HC it would be your privilege. He has a wealth of knowledge and a lifetime of experience. You would surely benefit even just a little.
I also was intrigued by your TR fixed pitch story for one clear reason! These excercises are inherently dangerous. Therefore you should NEVER instigate them in flight without a full and proper brief when instructing. The fact your student did not even realise what your were simulating by placing your feet on the pedals stirs my own inner instructor to the point of moral outrage.
Introducing exercises during training, especially flight control malfunctions that require a highly advanced diagnosis and subsequent flight profile, without a ground brief is dangerous and extremely traumatic for the student.
This also applies exactly the same for Flight Tests and Checks. All critical exercises must at least have a safety brief AND can even include guidance and confirmatory instruction to at least ensure safety is served.
H500 I know you will smart a bit and kick back at what I have written, however, if you truly want to take on the CAA or improve the standards of PPL skills generally look carefully at what I have written in conjunction with what HC also states about your students initial reaction. That SHOULD have been a clear indicator to you to say "Oh you are not sure....then let me give you a brief (possibly in flight) followed by some top notch demos (which I am sure you can do), followed by his practise. EXPLANATION, DEMONSTRATION, IMITATION.
Sitting there with your feet jammed on the pedals and letting the poor guy descend to 100 feet having no clue how to resolve the problem would have been horrific for that pilot. In my view you should seriously consider your conduct and the effect it would have had on this student.