Saint Piran's Flag is regarded by many as the national flag of Cornwall, and an emblem of the Cornish people; and by others as the county flag. The banner of Saint Piran is a white cross on a black background. Saint Piran is supposed to have adopted these two colours from seeing the white tin in the black coals and ashes during his supposed discovery of tin. Davies Gilbert in 1826 described it as anciently the flag of St Piran and the banner of Cornwall, and another history of 1880 said that: "The white cross of St. Piran was the ancient banner of the Cornish people". The Cornish flag is an exact reverse of the former Breton national flag (black cross) and is known by the same name "Kroaz Du".
There are also claims that the patron saint of Cornwall is Saint Michael or Saint Petroc, but Saint Piran is by far the most popular of the three and his emblem is internationally recognised as the flag of Cornwall. St Piran's Day (5 March) is celebrated by the Cornish diaspora around the world.