It's the bane of my life
Curious Pax
Not being able to land before 0600z at LHR causes me huge problems. I fly B777's for a well known British Airline and many of my flights originate on the East coast of the US with scheduled arrival times just after this time.
The problem stems from the very limited number of flights allowed to land during the night (Night slots) which ends at 6 AM. Any early "day" arrivals would use up these precious slots and jepordise the schedule of those flights. If the north Atlantic tailwinds are stronger than average it puts me in a quandary as you have seen. It is often not possible to remain on the gate at the departure airfield due to the next service needing it (and the gate being owned by that carrier) and holding on the airfield with such a large aircraft simply gets in the way.
My usual tactic is to depart on time, taxi as slowly as possible and then fly at mach .80 as opposed to mach .84. A sensible amount of extra fuel is loaded to cover holding over the London area for upto 30 - 40 minutes.
Given the vagarities of ATC, weather and unexpected delays/improvements you can see why I'm paid over £6.50 hour to sort it all out!!