One thing that's puzzled me for years. I was at Brize in about 1970; I had taken some cadets there and scrounged a ride in a Britannia (only a short one, 4.5 hours!) and were waiting for transport back to the terminal. Another Britannia was being readied for departure. Prior to start, one of the groundcrew went over and leaned against the prop of the engine about to be started. He suddenly walked forwards and as he did so, the prop started to turn. He did this with all 4 engines. Why was this? As the mighty Proteus was multiple spool, did he wait until he heard the turbine begin to wind up, effectively 'braking' the prop?