On 17 July 1945, the United Kingdom became a little smaller, and Yugoslavia a little bigger.
On the orders of Winston Churchill, suite 212 of Claridge's Hotel in London became Yugoslav territory, for one day only.
This allowed Crown Prince Alexander of Yugoslavia - part of the exiled royal family - to be born on home territory.
The front door became an international border. Room service was made in one country, and delivered in another.
The story of suite 212 is repeated on the Crown Prince's website, in the official history of Claridge's, and in countless books.
Just one problem. There is - it seems - no proof that it's actually true.
In April 1941, during World War Two, Germany and its allies attacked and occupied Yugoslavia, so King Peter II of Yugoslavia - then just 17 years old - left the country with his government, and travelled to London via Athens, Jerusalem and Cairo.
King Peter and his wife, Queen Alexandra, took up residence in one of London's most fashionable hotels, Claridge's, and it was here four years later that the queen became pregnant.
This presented the royal couple with a dilemma.
They wanted their first-born - and, in their eyes, the future king or queen of Yugoslavia - to be born in the country he or she would rule. But, with the war in Europe over, Yugoslavia was on its way to becoming a communist republic.
