E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Durham Mustard.
So called from the residence of Mrs. Clements, who first conceived the idea of grinding mustard in a mill, instead of pounding it in a mortar. George I. stamped it with his approval, hence the pots labelled “Durham mustard” bear the royal initials in a medallion.
