It has got top-hat liners!
Post mortem is throwing up some interesting info:
Torques required to loosen head bolts varied wildly, with a sort of pattern from back to front, back being "omigawd, are these ever going to crack or will my breaker bar break first" tight to front being "could have undone those with a 1/4 drive ratchet" loose. Now I know that a damaged gasket will allow some movement around the damaged area, so would expect those around #5 to be looser, but not the front ones.
Here's the head and gasket:
Gasket was genuine Land Rover- which I'd expect as last billed head work was LR main dealer.
Gasket on #5 was also burning through toward 3 of the studs
which indicates to me an issue with torquing.
Anyway, time for a good cleanup and deployment of straight edge on block...