[3] He went to Mass daily, and one morning, before it was light, found on the threshold of the church an abandoned child, whom he adopted and to whom he taught his trade.

Later he took a vow to visit the Holy Places, and, having received the consecrated wallet and staff as a Palmer, set out with his adopted son, whose name is given as "Cockermay Doucri", which is said to be Scots for "David the Foundling".

However, according to a popular account, David willfully misled his benefactor with a short-cut and, with robbery in view, felled him with a blow on the head and cut his throat.

[3] In 1256 Lawrence of St Martin, Bishop of Rochester, obtained the canonisation of William from Pope Alexander IV.

On 29 November 1399, Pope Boniface IX granted an indulgence to those who visited and gave alms to the shrine on certain specified days.

St William is represented in a wall-painting, which was discovered in 1883 in Frindsbury church, near Rochester, which is supposed to have been painted about 1256–1266, in which case it is also the only known mural of him.

In the film St. Vincent, St William is featured in a school report by one of the main characters, Oliver, who finds him interesting primarily because he himself is adopted.

The story of Saint William of Perth is also recounted by the character DS James Hathaway in series four, episode four, of Lewis.