The British Third Guinea coin is unique among the British gold coinage in having been produced exclusively in the reign of one monarch, in this case King George III.
When it was introduced in 1797 the financial situation at the Bank of England was very precarious -- gold was in short supply thanks to the effects of the French Revolutionary wars, and banknotes were given legal tender status in any amount. In order to pay the Bank's dividends it was decided to produce what at the time were known as seven-shilling pieces, with odd amounts of the dividend being paid in silver coins. A total of £315,000 worth of coins was authorised in October 1797. The denomination was struck each year until 1813, with the exception of 1805, 1807, and 1812. Between 1800 and 1812 third and half guineas were the only gold coins issued.
The coin weighed 2.8 grams and was 17 millimetres in diameter, with a milled edge. The design of the reverse changed in 1801 following the union of the parliaments of Great Britain and Ireland, when simultaneously the king relinquished his claim on the French throne (some four hundred years after it had ceased to mean anything). There were two obverses used, with different portraits of the king (the new one being introduced in 1804), with the legend GEORGIVS III DEI GRATIA. The design of the reverse was a crown, with the legend MAG BRI FR ET HIB REX date (to 1800) or FIDEI DEFENSOR BRITANNIARUM REX date (from 1801).
For other denominations, see British coinage.
