Silver 11.3mm diameter, wt. 0.40gram.  Triangle with fleurs-de-lis at points, a star each side.  Rv. + BETVNE around cross.  Ghyssens 219.  

Ex David Rogers collection.

William and his family were part of a family of nobles from Artois, He was also a baron in England and Flanders until at least the time of King John,