Saint Olaf was King of Norway from 1015-1030, having previously come to England as a Viking warrior. He strove to convert his country to Christianity, but his people turned against him and he was eventually defeated and exiled by the Danish King Cnut. Returning from exile in 1030, he was defeated and killed at the battle of Stikelstad.
He was buried at the Church of St Clement in Nidaros (now Trondhjem), where belief in his sanctity quickly spread. His cult spread widely in the middle ages and in England he was popularly revered, particularly in London. The badge represents an axe, the emblem of his martyrdom.