UK's cheapest supermarket unveiled - and it beats Tesco Clubcard and Sainsbury's Nectar prices

The study by Which? found that Aldi was £16.51 cheaper than Sainsbury's and £10.67 less expensive than Tesco for a comparable shopping list.

Which? compared the prices of 59 everyday grocery items across eight major supermarkets. Aldi's basket came in at an average of £102.68, approximately 10 per cent less than Tesco and Sainsbury's with their Clubcard and Nectar offers applied.

Lidl was a close second, with the same shop costing just £1.18 more at £103.86.

Asda followed as the cheapest of the traditional supermarkets at £112.19, narrowly undercutting Tesco and Sainsbury's loyalty prices.

At the other end of the scale, Waitrose proved the most expensive, with an average basket cost of £130.37 - a stark 27 per cent more than Aldi.

Tesco shoppers with a Clubcard would have paid £112.96 on average, while those without paid £113.35. Sainsbury's Nectar cardholders faced an average bill of £113.79, compared to £119.19 for non-members.

Morrisons came in at £119.18, whilst Ocado's basket totalled £125.16. The study included both branded and own-label items such as Birds Eye Peas, Hovis bread, milk and butter.

Ele Clark, Which? retail editor, commented: "Our latest monthly analysis once again sees Aldi crowned as the UK's cheapest supermarket.

"Given the ongoing strain of high food prices on household budgets, it's understandable many people are choosing discounters to cut costs."

Clark added that consumers could save 21 per cent by switching to the cheapest option, emphasising the importance of comparing prices.

The impact of loyalty schemes on supermarket prices was significant. Sainsbury's offered member-only Nectar prices on 19 of the 59 items, while Tesco had Clubcard prices on five.

Non-loyalty card holders paid five per cent more at Sainsbury's and 0.4 per cent more at Tesco on average.

Lidl, Morrisons and Waitrose also have loyalty schemes, but didn't offer discounts on the items in the September shopping list.

However, a recent Which? investigation raised questions about the fairness of loyalty pricing. It found that 10 per cent of Tesco's loyalty offers had been at the non-member price for less than half the previous six months.

Similarly, five per cent of Sainsbury's loyalty promotions had non-member prices in place less than half the time.

These findings suggest that the 'usual' selling prices for non-members may not always be a fair reflection of the product's value.

Which? also compared prices for a larger shopping list of 164 items, excluding Aldi and Lidl due to their limited range of branded goods. Asda emerged as the cheapest at £418.88, narrowly beating Tesco's Clubcard price of £418.89.

However, non-Clubcard members at Tesco would have paid £452.92, an eight per cent increase. Sainsbury's presented the most dramatic price difference for loyalty scheme members.

Nectar cardholders paid £421.16, making it the third-cheapest option. But non-members faced the highest bill at £461.29, surpassing even Waitrose at £459.45.

Morrisons (£446.76) and Ocado (£452.02) fell in the middle range. These findings highlight the growing importance of loyalty schemes in supermarket pricing strategies, with significant savings available to members at some retailers.