Hi gruntie,
"...engineers were up a gantry looking at the tail plane and scratching their heads. Chris, were you involved with this at all?"
Not me, guv! In the summer of 1967 I was flying a tiny airliner that happened to share the same engine-synchrometer as the VC10. Sorry I can't shed any light on that one. Have you read about BCAL's Andes incident, which damaged the TPI (tail-plane) on G-ASIX, the Type 1103 a/c now in Omani colours at Brooklands?