BRISTOLRE, BA have this year and last year switched to a 400 from a 777 around April/May time which I would hazard a guess as something to do with increased loads in the summer. Couple of years ago the LHR-PHX used to go onto SAN which was then a 400. I believe they switched over to a 777 when they stopped the shuttle.
BigAir, You can always risk an ID90 and spend your days trying to get on!
Job well done to all the crew!