If you believe General Sir Fartin Marndale did the Army Pilots Course you'd be very much mistaken. From memory, the present incumbent (4 Star) is probably the only one. He did the pilots course as a subaltern and served a tour as a line pilot; but that's it. The others, apologies if I missed any? Just turned up for a 3 week famil and got given a badge.
Scratching my head, General Kenny (4 Star) was also a line pilot but not sure he was ever Colonel Commandant?