Possibly to go with the rations, to stop them taking advantage. It stopped them going into one shop, taking their rations and going into another to get the same again, Etc.
+++
I'm not sure if anyone "registered" in the shops but they did need Government-issued ration-cards for most foods and many other commodities.
Britain had a coalition government during World War 2
Britain wasn't invaded during World War 2
Yes, he was the prime minister and military leader of Britain during world war 2
George V ( reigned from 1910 to 1936 ) was King of Britain during World War 1.
George VI was king of Great Britain during World War 2.
Britain's Prime Minister during World War I was David Lloyd George.
Britain was not invaded in World War 2 and there was no Holocaust in Britain.
during World War I, Britain had a very strong military.
London
Germany was Britain's main enemy.
The Battle of Britain occured during World War II not World War I.
It wasn't. The Battle of Britain was just one of many battles fought during World War II.