I think FAR 121.565 is pretty clear.
(a) Except as provided in paragraph (b) .. whenever an airplane engine fails or whenever an engine is shutdown to prevent possible damage, the pilot-in-command must land the airplane at the nearest suitable airport, in point of time, at which a safe landing can be made.
(b) If not more than one engine of an airplane that has three or more engines fails or is shut down to prevent possible dame, the pilot-in-command may proceed to an airport that the pilot selects ... if the pilot makes a reasonable decision that proceeding to that airport is as safe as landing at the nearest suitable airport.
I don't see how anyone can say continuing a flight across the pond is as safe as landing at the nearest suitable airport.
As far as BA's decision is concerned, I would assume that the UK rules have something similar.
Goldfish (who has moved BA to my personal "no fly list
