There was also a Mk2 Shack that was extremely sensitive in pitch - it had been damaged (IIRC) when someone drove a vehicle into the tail and virtually knocked it off, and the ac was rebuilt. It was only when they were all lined up for a royal visit that the groundcrew found they couldn't line up both front and back of the aircraft - it was some 2 or 3 feet shorter. On the rebuild they had missed out a couple of formers!!