VS8 lands at EGCC
Unforeseen circumstances?
LAX-LHR Unforeseen circumstances could mean less than favorable tailwinds, or possibly the ship being a bit thirsty or a longer track distance than planned which would appear to be the case here. Burning more fuel than planned would mean they would not arrive legally at LHR with fuel for LGW as alternate so the commander may have elected to rectify the situation.
Solution, drop into Manchester for a "splash and go"
Just a thought.