That's Tesco prices, and the rest seem to follow suit. And I was under the impression that the Supermarkets were supposed to be cheaper!!
I have to look after the company fuel account (we currently use Arval cards), so I keep an eye on fuel prices.
Shell prices are, believe it or not, usually as competitive as anyone.
If you want to check your own area quickly, use the following
http://www.petrolprices.com/