It was the BA217.

Diverted to Terceira Island in the Azores en route to IAD.

Flight number Departing from Arriving at Scheduled time of arrival Time of arrival Estimated or actual
Information updated 1 minute ago.
BA0217 TER IAD 24 AUG 13:40 25 AUG 14:15 Estimated
BA0217 LHR TER 24 AUG 15:31 24 AUG 15:31 Actual

It was 747 G-BYGD with 300 pax (14F/70J/30W/185Y)

Another 747 us being sent out in the morning to continue the journey.