Asda Grantham

It was a close-run thing this week. But when it comes to a full selection supermarket, no one can catch Asda right now.

At £57.86, Asda was just 93p cheaper than Morrisons. It offered the cheapest price for 19 of the 33 items on our list, with 13 of these exclusively cheapest. These included the baby corn, chicken drumsticks, Genius pancakes and Milano salami.

Morrisons meanwhile was cheapest on 15 lines, 10 exclusively so. It was cheapest for products such as the Fever-Tree tonic, Lactofree milk, peppercorn sauce and white bread.

Asda’s own comparison site - which only matched the price for 21 items against Morrisons - found that its rival was actually cheaper for these products and thus the retailer had to offer our shopper an Asda Price Guarantee voucher worth £5.83.

The biggest single price difference between the two retailers was the Windolene wipes, which were £1.18 cheaper at Asda (see right), though the average differential hasn’t always been that significant.

Third-placed Tesco was almost a fiver more expensive than Asda this week at £62.79. Our shopper received a Brand Guarantee discount of £2.67. This would have only been £1.49 had she been able to pick up the Windolene wipes as the discount was based on its prices versus Morrisons - the cheapest retailer for the branded lines on our list.

This would have taken Tesco’s total shopping bill down to £61.30, still £3.44 more expensive than Asda and £2.51 more than Morrisons.

Sainsbury’s and Waitrose were both a long way off the pace. At £65.58, Sainsbury’s came out £7.72 more expensive than Asda, while Waitrose was £12.72 more expensive, with the difference particularly pronounced on fresh items such as the baby new potatoes and ­butternut squash.