The most recent Which? price comparison analysis asserts that Lidl is the cheapest supermarket for the fifth month in a row.

The sample basket of 18 groceries cost £25.92 at the discount supermarket, compared to £35.06 at Waitrose. Asda was the cheapest of the traditional supermarkets for this small basket of items at £28.46.

Which? tracks the prices of up to 200 branded and own-label products every day over the course of a month to work out the average cost per item, then adds those averages up to get a trolley total for each retailer, producing a monthly price comparison analysis.

Which? also compares a larger trolley of 63 groceries (the original 18 plus 45 more) each month. Asda, which has been the cheapest traditional supermarket every month since January 2020, was the cheapest for the bigger trolley of items at £132.81. It was £17.01 cheaper than Waitrose.

Aldi and Lidl were added into the price comparison analysis back in 2020. Data is supplied by an independent price comparison company.

Food inflation rose to 3.5 per cent in April, up from 3.3 per cent in March, making it the highest figure on the index since March 2013.

Reena Sewraz, Which? Money expert, told the website inews: “With household bills and food prices going up, it’s no surprise that budget supermarkets have seen an increase in footfall recently and we’ve found you can buy many of the same groceries for a much better price than at one of the ‘big four’ supermarkets.”