 Dunstan became patron saint of English goldsmiths and silversmiths because he worked as a silversmith making church plate . His Feast Day is 19 May , which is why before the restoration the date year on London Assay Office hallmarks ran from 19 May one year to 18 May the next , not the calendar year . This was changed at the restoration of Charles II in 1660 so that the hallmarking year began on the King 's birthday , 29 May . 
