The pound is the currency of Guernsey. Since 1921, Guernsey has been in currency union with the United Kingdom and the Guernsey pound is not a separate currency but is a local issue of sterling banknotes and coins, in a similar way to the banknotes issued in Scotland, England and Northern Ireland (see Banknotes of the pound sterling). It can be exchanged at par with other sterling coinage and notes (see also sterling area). For this reason, ISO 4217 does not include a separate currency code for the Guernsey pound, when distinction from sterling is desired the abbreviation GGP may be used. History Until the early 19th century, Guernsey used predominantly French currency. Coins of the French livre were legal tender until 1834, with French francs used until 1921. In 1830, Guernsey began production of copper coins denominated in doubles. The double was worth of a French franc. The name "double" derived from the French "double deniers", although the value of the coin was equal to the liard (three-denier piece) still circulating. Coins were issued in denominations of 1, 2, 4 and 8 doubles. The 8 double coin was a "Guernsey penny", with twelve to the "Guernsey shilling" (worth 1.2 francs). However, this shilling was not equal to the British shilling (worth 1.26 francs, as the exchange rate according to the respective gold standards was 25.22 francs = 1 pound sterling). Banknotes were also produced by the States of Guernsey from 1827, denominated in pounds. In 1848, an ordinance was passed that the pound sterling should be legal tender at a value of £1 1s 3d (2040 doubles). This was rescinded two years later and French currency, supplemented by local issues, continued to circulate. In 1870, British coins were made legal tender, with the British shilling circulating at Guernsey pence. Bank of England notes became legal tender in 1873. In 1914, new banknotes appeared, some of which carried denominations in Guernsey shillings and francs. After the First World War, the value of the franc began to fall relative to sterling. This caused Guernsey to adopt a pound equal to the pound sterling in 1921. For amounts below 1 shilling, the conversion rate of 1 Guernsey penny (8 doubles) = 1 British penny applied, allowing the Guernsey coins to continue to circulate. For amounts above 1 shilling, an exchange rate of 21 Guernsey shillings to the pound sterling was used, applying