Envelope front (only), signed ‘Cambridge’ lower left, addressed ‘To The King, Hanover’. 2¾ x 4¾ inches, laid down on part of an album page, traces of mounting on verso, other minor blemishes. Undated. Adolphus Frederick, Duke of Cambridge (1774-1850), tenth child of King George III and Queen Charlotte. In 1816 the Duke of Cambridge, on behalf of King William IV, was appointed to the viceroyalty of Hanover, which at the treaty of Vienna (1814) had been elevated from an electorate to a kingdom. His discreet administration helped to preserve the Hanoverian crown for his family.