Originally Posted by
phol
They're random swaps on the BA27/28 flights, and they happen often.
I don't know how often last minute swaps take place, but the scheduled pattern during the current season appears to be pretty stable.
ex-LHR
Mon: 77W
Tue: 772
Wed: 77W
Thu: 77W
Fri: 772
Sat: 77W
Sun: 77W
One day later ex-HKG, of course.