THE Queen joked "you can't cheat then?" as she was shown the self-service tills while visiting Sainsbury's to mark the supermarket's 150th anniversary today.
The 93-year-old monarch inspected the technology this morning as she toured the replica store - saying they were sure to help people who were "in a hurry".
As part of the visit, she was told about how rationing was developed during wartime, to how families now use self-service tills to get their weekly shop.
Speaking to manager Damien Corcoran, she appeared to be particularly interested in the self-service checkout facility - wondering if it was possible to get away without paying.
She asked: "And you can't trick it? You can't cheat then?"
Mr Corcoran replied: "Well, you always can cheat but with the weighing scales we've got that should prevent certain items from being undetected."
The Queen had a point -
with Brit shoppers previously admitting to nicking billions of pounds in groceries - just because they can.
Mr Corcoran then told her many shoppers like the convenience of scanning their own groceries, with the monarch remarking: "I'm sure they do - everybody wants to hurry."
Her Maj was even greeted by period actors dressed to fit the pop up store - a replica of the original 1869 Sainsbury's store in Drury Lane in Covent Garden.
Then, the store sold just three items - butter, milk and eggs.
She was later shown Bloater Paste, a fish herring pate from the 1950s, which she said "sounded disgusting".
During her visit, the Queen also got the opportunity to see an original ration book from the Second World War, and reflected on her own experiences of food shortages.
She said: "As a Sunday treat we had some sweeties, but we were lucky we had a farm."
When the porridge and oranges of six decades ago were contrasted the avocados and ready meals of 2019, she remarked "tastes have changed".