Well I can't remember much about it, but Team 21 in the 1959 750MC Six Hour Relay was the Octagon Stable MGA-Twin Cams.
Car C was P.G. Fletcher's and he spun and rolled his car at Copse, according to the Motor Sport report, and the damage looks appropriate.
I found a statement that he had the body modified by Peel engineering and the engine by Barwell so it didn't look like the MGA it really was.