Originally Posted by
Mark_T
Yes you will see LFBU offered on the kiosk if it is available but there isn't any set time as it depends on the wait list having been cleared first and that is often not happening until an hour or so before take-off.
AAngels are no help to you for this sort of thing as the upgrades are kiosk only.
The upgrades are kiosk only?! Well, I've definitely never seen them at LHR. Flying this route since 1987.
I was denied boarding once (fairly recently) on a flight when I arrived at check-in, no bags, 1 hr 58 mins in advance... so I don't recommend trying to hit that kiosk late. (I was in T3 flying LHR>BOS.)