Tesco Express shoppers warned they face having to pay £520 charge

Which? compared the cost of 42 popular grocery items – from cheese and pasta to blueberries and ice-cream – on three occasions in June and July.

Tesco Express shoppers pay £10 extra a week - or £520 a year - according to a Which? study. Which? compared the cost of 42 popular grocery items – from cheese and pasta to blueberries and ice-cream – on three occasions in June and July.

The study involved the largest supermarket-branded convenience chains – Morrisons Daily, Sainsbury’s Local and Tesco Express – against prices at their full-sized supermarkets. The biggest price difference for the items compared by the consumer group – branded and own-label – was at Morrisons.

It found shoppers would pay 21% more on average for the same groceries at a Morrisons Daily than at one of its large supermarkets. In response to the study, Tesco said that it tailored its Clubcard Prices loyalty offers at smaller stores as customers tended to buy for different occasions there. Which? collected data from a total of 11 convenience stores and nearby supermarkets around the country, from Glasgow to Sevenoaks in Kent.

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Members of Morrisons’ loyalty scheme More could pay 22% extra at its smaller outlets as the card is not currently accepted there. Morrisons said it was “actively working” on introducing the More card to Morrisons Daily stores “in the coming months”.

Which? explained: "The total cost of our basket of groceries averaged £16 more at Morrisons Daily than Morrisons supermarkets, meaning you could shell out a massive £832 more over the course of a year if you bought that selection of products once a week.

"In total, our 42 groceries would have averaged around £11 (14%) more at Sainsbury’s Local than Sainsbury's supermarkets, and £10 (11%) more at Tesco Express than Tesco supermarkets for loyalty members, which adds up to more than £500 extra over a year."

Overall, Tesco Express was the cheapest of the convenience stores – but only if you have a Clubcard - Which said.