In the course of the twelfth century, if not earlier, a very general practice grew up at well-known places of pilgrimage, of casting tokens in lead, and sometimes probably in other metals, which served the pilgrim as a souvenir and stimulus to devotion and at the same time attested the fact that he had duly reached his destination. These "signacula" (enseignes) known in English as "pilgrims' signs" often took a metallic form and were carried in a conspicuous way upon the hat or breast. Giraldus Cambrensis referring to a journey he made to Canterbury about the year 1180, ten years after the martyrdom of St. Thomas Becket, describes himself and his companions returning to London with the tokens of St. Thomas hanging round their necks. They are also mentioned in the allegorical poem Piers the Plowman. The privilege of casting and selling these pilgrim's signs was a very valuable one and became a regular source of income at most places of religious resort.