Who is actually responsible here? What team at BA has responsibilty for the customer experience at UK outstations? And who heads that team? Only a concerted effort towards a names individual will make any progress IMHO. Classic benign neglect here, no one cares enough to drive change.
No name, no accountability, no chance. And no, I don't mean a witch hunt. I just mean challenging the toleration of service levels that their predecessors would have been dismissed for.