The box - which originally contained just a single bar of Rowntree's chocolate - is one of the rarest commemorative wares produced for the royal event. Auctioneers at David Duggleby believe it is only the second to be seen in an auction this century. For the coronation, Rowntree's of York - alongside all the country's major chocolate manufacturers - produced thousand of souvenir coronation tins which were distributed across the nation. They were decorated with painted portraits of the King Edward and Queen Alexandra. The King and Queen supplied tins of the Rowntree chocolate for Coronation Dinners that were arranged for 'the poor of London' and for a Royal housemaids tea.