BA 280 LAX - LHR according to the November menu the champagne is either Lanson, NOBLE Brut Vintage or Blanc de Blancs 2005. They wouldn't say which one would be on board; a bit too clever for me. I suspect the BdB05 is the better and less available one, so expecting the former. I'm flying this route in a few days, so haven't verified this onboard.
Cheers,
-Cyborg