Retail margins on petrol have fallen, according to the AA, and prices have continued to fall.

In its latest AA Fuel Price Report, it says: "AA research finds that during the periods of early 2014, early 2015 and late 2015, subtracting the cost of wholesale, ethanol and tax from the pump price leaves a fairly consistent 8ppl. This covers retailer and supplier margins, transport and other costs (including VAT). That gap has now closed by around a penny a litre, pointing to lower margins in the retail sector."

Tesco and Morrisons followed after Asda cut 2ppl off the price of diesel, bringing its national price cap down to 97.7ppl while unleaded remains at 99.7ppl.

Andy Peake, Asda’s senior petrol director, said: "This shows that we’re committed to being the driving force behind lowering fuel prices across the UK regardless of where you live."

RAC fuel spokesman Simon Williams said: "We would have liked to have seen a cut sooner, and one that goes further, to more closely reflect the price retailers have been buying diesel for, but this is good news for motorists.

"Diesel has been sold on the wholesale market for less than unleaded petrol since early last month, yet drivers have had to wait more than six weeks for this to be only partially reflected at the pumps."