Below average petrol

I heard on the news the other day that UK petrol prices had reached an average price of £1.40 per litre for unleaded petrol. This surprised me, since it's been over £1.40 for many months at the petrol stattion I drive past every few days. At that petrol station today, it was 147.8p per litre, but I passed another one at selling it at 148.9. So where is all this petrol selling for a lot under £1.40, to counter all this expensive petrol and bring the average down? (As context for Americans: If I've done my conversion calculations correctly, 148.9 pence per (UK) litre is the equivalent of nearly $9 per American gallon.)