Fuel also does not cost the same all over the world, and presumably, BA must refuel their birds not just in the UK. SAA, for example, fills its daily 747 to Lagos from JNB with enough fuel so as not to have to take on fuel in Nigeria, where it seems to be very expensive (despite being a lrge producer). I imagine BA factors in fuel prices at all its destinations... I know aircraft fuel in SEA is cheaper than that in LAX for some odd reason I do not understand.

Also, if I understand it correctly, today's fuel prices do not reach consumers and businesses (including airlines) until months later. So the fuel being consumed today is actually fuel extracted and paid for many months ago. At least, that is how I vaguely understand it. I am sure there is someone in petroleum on this board who understands it much better...

There are also some groups who say the fuel surcharges reflect the "true cost" of air travel, whatever that means.