Sainsbury’s and Morrisons do not currently offer member-only discounts in their convenience stores so the total average cost of the grocery basket was the same regardless of membership. The average was £111.83 at Sainsbury’s and £119.29 at Morrisons.

Popping to your local shop could be costing you as much as £832 extra a year than going to the supermarket. Which? collected price data on 42 items which were commonly purchased from Morrisons Daily,

The biggest price difference was at Morrisons Daily, where shoppers paid 21 per cent more on average, followed by 14 per cent at Sainsbury's Local and 11 per cent at Tesco Express.