Just like every other family in the country, the Royals had to follow strict rationing rules during the Second World War.
They had their own ration books for food and drink, and the Queen even had to save up the coupons to buy the material for her wedding dress.
The monarch, who was Princess Elizabeth at the time, reflected on the system as she stepped back in time and visited mocked up Sainsbury's store from 150 years ago.
During her visit, which marked the supermarket chain's 150th birthday, she was shown an original ration book from the Second World War.
She said: "As a Sunday treat we had some sweeties, but we were lucky we had a farm."
There was also a demonstration of a shopping basket from the 1950s, containing a herring paste that the Queen described as "ghastly".
When the porridge and oranges of six decades ago were contrasted the avocados and ready meals of 2019, she remarked "tastes have changed".
She also got to see some of the more modern features the store offers, including the self-service check outs.
She was given a demonstration of the self-service tills and had a rather cheeky question for her host.
When manager Damien Corcoran showed her how they worked, she asked about people "cheating" on the machines.
With a big smile on her face, she said: "And you can't trick it? You can't cheat?"
Damien replied: "Well, you always can cheat but with the weighing scales we've got that should prevent certain items from going through the till undetected."
She was also shown a new shopping app, which she called "an interesting tool".
The Queen, who was wearing a mint green coat, was greeted by Lord John Sainsbury, the great-grandson of the supermarket chain's founder John James Sainsbury.
