Note...do this at the check in counter...not the gate. They generally cannot process any payments at the gate check-in desks and in many cases they do not have the authority to make the change.
While I am sure Greg knows better than me on this as he flies BA across the pond all the time, I actually found that on the Euro flights, I got nowhere at the check-in counter, nowhere at the ticket desk, but only got joy at the gate and on the plane itself.
On the GB Airways (who operate BA flights) internal system, it says to process these on board with the purser.
Aussiestu wrote...and so they should be. Why upgrade at all, pay the price and then you travel in that cabin.
Well part of the price you pay is to gaurantee your seat, if most business men were told the fare would be 1000 dollars less if they relied on there being space on the day for them to get an upgrade, I still think most would pay the full fare to be sure that they get the seat