Ivory was used all over Europe for religious works of art. It was often combined with precious metals and usually took the form of relief panels, for book covers, portable altars and caskets. An almost unbroken tradition of ivory carving extends from the Roman and Byzantine empires until the end of the 14th century. From ca. 1250, Paris became the centre of production for figures and reliefs intended for private devotion.

This head of a tau-cross in walrus-ivory, is of Anglo-Norman origin and from the first quaerter of 12th century.
It has long been recognised that the present tau cross head is intimately related to a walrus ivory fragment showing a man entangled in foliate scrolls now in the British Museum, and it has even been thought to be of the same hand. The latter was found in 1920 on the site of the monastic infirmary at St. Albans.