Thanks, folks -- looks like staying airside and taking the transfer bus is the plan. Now I'm starting to question whether I can have my United boarding pass in hand when I arrive at LHR. Anyone happen to know if in Prague, BA could check me in for the United flight? Different record locators and alliances. United has no operations in PRG. I don't think I can check in online for this (could not on the outbound, SFO-LHR).