HOW IT WORKS (WITHOUT YOU KNOWING WHAT YOU SPENT)

1 You need a smartphone. Download the Amazon shopping app, and add payment details to the shopping account.

2 Before you enter the store, you press an ‘Amazon Fresh’ link in the app. This creates a QR barcode on your phone screen. This is scanned by a reader at the shop entrance, opening a barrier to let you in.

3 You pick up a free paper bag – or a £1 ‘green’ bag – and fill it with the goods you want to buy. As you pick an item off the shelf, an ultra-sensitive ‘sensor fusion’ weighs what has been taken. This is supported by ‘computer vision’ where cameras around the store confirm that you put the item in the bag.

4 You step up to the exit barrier and it opens automatically.

5 Money is taken from the card linked to your Amazon app. An itemised email arrives with details of how much you have spent. You can also log on to your Amazon shopping account to view details.