Columbus, we are told, sailed over the ocean blue and discovered North America in 1492. However, the jingle is widely disputed; behind Columbus there is a long queue of explorers who are, from time to time, pushed forward as the ‘real’ discoverers of America – the Portuguese, who are alleged to have arrived a generation before Columbus; the English, more specifically a Carmelite Friar, Nicholas of Lynne, who ventured into the polar region in the 14th century; Madog, the Welsh prince who is said to have set up a Welsh colony in Alabama in the 12th century; and the Vikings, whose ‘Markland’ is widely thought to be Labrador, Canada.