Plympton became the fourth Devon stannary town in 1328 after a powerful lobby persuaded the Sheriff of Devon that it was nearer the sea and therefore had better access for merchants.
In March 2007, Bridget Prentice, Parliamentary Under-Secretary of State in the Ministry of Justice, stated in a Commons written answer that "there are no valid Cornish stannary organisations in existence" and that there "are no treaties today that apply to Cornwall only".