A mate of mine was flying an instructional sortie with a student who was having trouble with glide circuits in the mighty Parrot. Student realised he was going to fly through the extended centreline so he very rapidly applied bank and pulled, stalling the aircraft. Instructor called “taking over” and shook the stick, but the student froze and would not release the controls. At this stage the aircraft was about 400FT AGL and stalled. Instructor had to thump the student in order for him to release the controls. And that was the last sortie that student ever flew in a CT4.