Next Monday I'm on BA27 to HKG. I'm flying in from DUB on the same ticket at 1320 so loads of time at LHR. But just noticed that BA31 (which leaves 90 mins earlier) now has F class. I'm sure as sure it didn't when I booked 9 months ago.

But, BA31 is the old 777 with 14F. Is this going to be much of a downgrade to the 789? In other words, will I be given up much to save 90 minutes? GGL so no cost to change (reward booking)