It seems to me that when the cost of a ticket does go up its usually down to another increase in some form of tax. I also seem to remember a fuel surcharge going up last year, has it gone down now?
The last time the price of oil was at the level it currently is, BA's fuel surcharge for long-haul flights was £24 per sector; today it's up to £86.50 in economy and as much as £118 in Club World. The whole "fuel surcharge" scenario is a con intended to squeeze money out of the most loyal customers - corporate customers who are entitled to a discount of the base fare and those purchasing a flight using frequent flyer points.
A couple of days ago I investigated the cost of booking a "free" flight in Club World from London to Sydney and back. Taxes and charges amounted to almost £500 - and there'll be an additional £120 fee soon for not wishing to sit in the worst seats on the aircraft.