Today, I paid $1.399 per litre for regular gas. That would be approximately $5.40 per US gallon or $6.30 per Imperial gallon. These are Canadian prices. In USD this would be $4.63 and $5.40 per gallon, respectively.
Here in Switzerland yesterday I paid CHF1.87/litre (approx 81.8p/litre) for Shell V100 (local equivalent to Optimax I believe). I think regular 95 octane unleaded was about CHF1.78 (77.8p/litre). Diesel is - surprisingly - about CHF 0.10 more expensive.
Gas (petrol) prices are dictated by many factors which differ among countries. Typically, consuming nations try to tax the heck out of it because it's something everyone one finds hard to do without - just as tobacco and alcohol attract tax. In nations which produce a lot of oil, the price of petrol is often kept very low - close to the cost of production, usually because these are often poor nations in other respects and because of historical precedent so that the citizens get this "break" and thus keep the politicians in power. Free beer or perhaps cocaine might do that in the UK?
In Europe we pay a lot of tax on fuel and in the UK, we pay the most, see this table (there is something wrong with the Danish tax figure but it looks correct apart from that).
So when people blame the oil companies for the cost of their fuel, they have chosen the wrong target.
There is also a lot of BS about all petrol being the same. This just isn't so. Even when companies sell petrol to third parties from their refinery this is no evidence for the stuff being the same, any more than if you compared the alcohol in bonded whisky warehouses. The fact is that petrol properties are modified by additives that frequently get added only at the depot level. Differentiation of fuels is very real, very competitive and very expensive for the oil companies. It can also make a huge difference in performance of engines, far outweighing the cost differentials. However, not all engines respond in exactly the same way.
Disclaimer: I used to work for an oil company so I know what I am talking about but you are also welcome to say I am biased.