I was a Flt Sys guy on 3 at Gut in the 70's, Pete Squier, later head of the RAF I think was a Flt Commander at the time. It was indeed an extraordinary aircraft, I remember John doing his famous rotation from the hover to the vertical and climb out. It's amazing to think that it's 50 years this last Nov19th since the prototype achieved free flight. Bit like Bleriot Monoplanes still being in service when Bill Bedford flew the P1127.