But BA stopped calling it a fuel surcharge years ago.

It's now a cute work around to improve the bottom line. Discounts can be offered on the base fare (incl frequent flier redemptions) yet the carrier surcharge remains untouched.

And your maths don't take into account the fact that BA probably hedged the cost of the fuel some way above where it is today. Not that that's an excuse - they're ultimately an airline, not a commodities trading business.