Not sure how much Opec is to blame for this one. The price of a barrel of oil is half of what it was in July 2008 (it has been rising recently but has fallen all week) yet the price of a litre of petrol is not half of what it was in July 2008.
July 2008 - £1.18 per litre (national supermarket average)
Dec 2009 - £1.06 per litre (national supermarket average)
So it's 10% less when it should really be 50% less and around 53p per litre.
So I'm guessing it's the fuel/refinery companies are keeping the majority of the extra difference (some has gone in duty and vat increases of course but Dec was still 2.5% less VAT than July 2008 so would offset some of the tax increases anyway).
Easy for them to let OPEC take the blame as most people do when they hear that the price of a barrel of oil is rising and hence next week the cost of petrol at the pump increases.
The truth is they never dropped the price of petrol to as low as they should have done. AFter all Shell has to try and keep making its £20billion and Bp it's £10billion annual profits which is hard to do if the price of crude drops unless you don't drop your pump price by as much as you should.