The legend runs like this.

After the death of King Uther Pendragon, Britain had no king, and a sword appeared driven into a stone anvil in a London churchyard.

Around the blade were the words: whoever pulls this sword from this stone is the true-born king of all Britain.

Knights tried, sweated, failed.

Then a squire named Arthur, sent to fetch a sword for his older foster-brother, pulled it out casually because his brother had forgotten his own.

There were actually two swords: the one from the stone, and Excalibur, given later by the Lady of the Lake.

The story was polished into its familiar shape by a French poet, Robert de Boron, around 1200, and reworked into English by Thomas Malory in Le Morte d'Arthur in 1485.

Britain has been trying to be Camelot ever since.