BA used LBA & NCL for some LHR diverts - certainly not normally considered.
we do actually see a fair few of BA heavys , During bad snow a few year ago we had 2x 744 2x 777 and a 767 in at once IIRC. Part of the reason BA flew their 787 here during training was also to get ground crew familiar with the aircraft such as Newcastle being one of their diversion airports according to the pilot.
Still it was poor from MAN last night