Brian Hindmarch of Walker had admitted taking the award given in the 1930s to Arthur Henderson, a pioneer of the Labour Party and campaigner for disarmament, during a raid at the Jesmond premises in April.
Also in the haul - valued at around £150,000 - were a lock of hair from Admiral Lord Collingwood (who commanded the British fleet at Trafalgar after Nelson's death) and a large amount of silver including four presentation cups to commemorate peace with Germany after the First World War and a snuff box from 1897.
None of the items has been recovered, despite a £30,000 reward being offered, the BBC has reported.
Charged with two counts of burglary, Hindmarch was sentenced to six and a half years in prison at Newcastle Crown Court last week.
