On a flight ARN-LHR on BA a year or so ago I found someone in my seat who had the exact same seat assignment on his BP. Brought over the stewardess who left with our BPs, came back a minute later and told my wife and me that we were flying "in front of the curtain". I guess it was an operational upgrade that should have been caught as we were boarding. In either case I said thanks and enjoyed the hot breakfast.