BOAC
If he was flying a circling/semi visual approach (if the reports are correct, he did call Rwy AND terrain in sight), he might have been confident enough to deviate away from his ordinary circling pattern.
He should have a lot of bells and whistles going off in the cockpit, but again, if he had the mountains in sight?
I've flown myself into GPWS/EGPWS territory during visual letdowns, and as per SOP, continued since I had the terrain clearly in sight.