During the second world war, food rationing was implemented and affected everyone in the U.K.- even Queen Mary had a ration book! The ration book was taken to the shop that the resident chose as “their” shop- no shopping around was permitted. The ration book gave you “permission” to buy a certain quantity of rationed items- you still had to pay for it. It was a way to prevent hoarding, black market activity, and shortages.
Special rations were permitted for special needs- growing children, chronically ill or aged people, vegetarians, etc. Ration books were carried with you with your identity papers as it was expensive and difficult to get a replacement if one was lost.
Limits placed on food averaged about 113 g per person per week for pork and bacon, 227 g ground beef, 113 g drippings (pork and beef fat, suet), butter 57 g, Margarine 113 g , tea 57 g, eggs 1 , cheese 57 g , 3 pt milk, 227 g sugar. Bread was not rationed, but only National Loaf (wholemeal enriched bread) was sold.
When staying in a hotel, the ration book had to be presented and was stamped as rations were eaten. In one episode of The Body in the Library, the Geraldine McEwen Miss Marple and her friend Dolly Bantry were seen turning in their ration books upon check in.