A quick question on the mechanics of doing this, for someone who will be transferring to BA at LHR from an LH flight on a separate ticket, and who we must assume will have no access to phone or data services at this point. He's booked on a BA flight to EDI which is probably later than he really needs but which has been chosen on the basis of safety, with an eye on the possibility that a change to an earlier flight might be feasible if he gets through the transfer process relatively swiftly.

Assuming that his bag cannot be through-checked to BA and he will need to go from T2 to T5 on the HEX, if he gets to T5 early enough to ask to be moved to an earlier flight, is his best bet to head for the Zone E ticket desks to try to get moved? If not, where should he go?

And if by some miracle his bag is through-checked (or at least through-tagged) to his originally-booked BA flight, so that he comes across the airfield on the inter-terminal airside transfer bus, can the transfer desks in flight connections do the change for him? Presumably if they can do that, then the bag will (ie should) itself get automatically rebooked onto the new flight at the same time?