It advocates unity of the monetary system throughout the entire state, with strict integrity in the quality of the coin, and the charge of a seigniorage sufficient to cover the expenses of mintage.
One of the most important duties of the warden was the collection from the contractor of the seigniorage which was claimed by the sovereign by virtue of his prerogative as a source of revenue to the Crown.
The right of levying seigniorage, however, was sometimes waived by the king to encourage his subjects to bring gold and silver to the mint, and several instances are recorded in which the aid of alchemists was called in to effect the transmutation of baser metals into gold.
Seigniorage was abolished for both gold and silver in 1666, when it was provided that no charge should be made at the Mint for coining and assaying.
It corresponds to the seigniorage levied by the king on all coinages down to the reign of Charles II.