Well, GBP 80 (or USD 160) for the FC APD to start with. A further GBP 11 or so to BAA (LHR usage fee). Some $15 to the U.S. government for entry into the U.S. That's about $200. Not sure where the $100 goes to a BA's fuel surcharges are much higher than this (unless there's a lower one for awards).