if oil is sold in u.s. dollars and the sterling/dollar exchang rate is the best it has been for a very long time,should petrol in the u.k. not be dropping in price rather than rising? maybe i am missing something!
You're looking at it the wrong way around though. The demand (and supply) worldwide is what sets the price, and most of the world does not use US$. So what actually happens is that when the value of the dollar goes down, the price goes up (in dollar terms, not necessarily real terms).
If the pound is getting stronger in its own right, then the price of oil (and most imports) should fall. But that's not the case -- it's actually the dollar that is getting weaker, which pulls the dollar value of oil upwards, and in turn means it costs us roughly the same as the increased $/£ ratio roughly cancels out the increased $ price. The pound is actually trading pretty low against the euro right now, so sterling isn't particularly strong in the big picture -- it's just a lot stronger than the dollar.
Or something like that
