The pound sterling is the world's oldest currency still in use.

Anglo-Saxon

The origins of sterling lie in the reign of King Offa of Mercia, (757–796) who introduced the silver penny. It copied the denarius of the new currency system of Charlemagne's Frankish Empire. As in the Carolingian system, 240 pennies weighed 1 pound (corresponding to Charlemagne's libra), with the shilling corresponding to Charlemagne's solidus and equal to 12d. At the time of the penny's introduction, it weighed 22.5 troy grains of fine silver (30 tower grains; about 1.5 g), indicating that the Mercian pound weighed 5,400 troy grains (the Mercian pound became the basis of the tower pound, which weighed 5,400 troy grains, equivalent to 7,200 tower grains). At this time, the name sterling had yet to be acquired. The penny swiftly spread throughout the other Anglo-Saxon kingdoms and became the standard coin of what was to become England.

Mediaeval

The early pennies were struck from fine silver (as pure as was available). However, in 1158, a new coinage was introduced by King Henry II (known as the Tealby penny) which was struck from .925 (92.5%) silver. This became the standard until the 20th century and is today known as sterling silver, named after its association with the currency. Sterling silver is harder than the fine silver (i.e. 0.999/99.9% pure, etc.) that was traditionally used and so sterling silver coins did not wear down as rapidly as fine silver coins. The English currency was almost exclusively silver until 1344, when the gold noble was successfully introduced into circulation. However, silver remained the legal basis for sterling until 1816. In the reign of Henry IV(1399–1413), the penny was reduced in weight to 15 grains (0.97 g) of silver, with a further reduction to 12 grains (0.78 g) in 1464.

Tudor

During the reigns of Henry VIII and Edward VI, the silver coinage was drastically debased, although the pound was redefined to the troy pound of 5,760 grains (373 g) in 1526. In 1544, a silver coinage was issued containing just one third silver and two thirds copper—equating to .333 silver, or 33.3% pure. The result was a coin copper in appearance, but relatively pale in colour. In 1552, a new silver coinage was introduced, struck in sterling silver. However, the penny's weight was reduced to 8 grains (0.52 g), meaning that 1 troy pound of sterling silver produced 60 shillings of coins. This silver standard was known as the "60-shilling standard" and lasted until 1601 when a "62-shilling standard" was introduced, reducing the penny's weight to 7 ²³⁄₃₁ grains (0.50 g). Throughout this period, the size and value of the gold coinage fluctuated considerably.

Unofficial gold standard

In 1663, a new gold coinage was introduced based on the 22 carat fine guinea. Fixed in weight at 44½ to the troy pound from 1670, this coin's value varied considerably until 1717, when it was fixed at 21 shillings (21/-, 1.05 pounds). However, despite the efforts of Sir Isaac Newton, Master of the Mint, to reduce the guinea's value, this valuation overvalued gold relative to silver when compared to the valuations in other European countries. British merchants sent silver abroad in payments whilst goods for export were paid for with gold. As a consequence, silver flowed out of the country and gold flowed in, leading to a situation where Great Britain was effectively on a gold standard. In addition, a chronic shortage of silver coins developed.

Establishment of modern currency

The Bank of England was formed in 1694, followed by the Bank of Scotland a year later. Both began to issue paper money.

Currency of the United Kingdom

The pound scots had begun equal to sterling but had suffered far higher devaluation until being pegged to sterling at a value of 12 pounds scots = 1 pound sterling. In 1707, the Kingdom of England and the Kingdom of Scotland merged to form the Kingdom of Great Britain. In accordance with the Treaty of Union, the currency of the 'united kingdom' was sterling with the pound scots being replaced by sterling at the pegged value.

Gold standard

During the Revolutionary and Napoleonic wars, Bank of England notes were legal tender and their value floated relative to gold. The Bank also issued silver tokens to alleviate the shortage of silver coins. In 1816, the gold standard was adopted officially, with the silver standard reduced to 66 shillings (66/-, 3.3 pounds), rendering silver coins a "token" issue (i.e., not containing their value in precious metal). In 1817, the sovereign was introduced. Struck in 22-carat gold, it contained 113 grains (7.3 g) of gold and replaced the guinea as the standard British gold coin without changing the gold standard. In 1825, the Irish pound, which had been pegged to sterling since 1801 at a rate of 13 Irish pounds = 12 pounds sterling, was replaced, at the same rate, with sterling.

During the late 19th and early 20th centuries, many other countries adopted the gold standard. As a consequence, conversion rates between different currencies could be determined simply from the respective gold standards. The pound sterling was equal to 4.85 U.S. dollars, 4.89 Canadian dollars, 12.10 Dutch guilders, 25.22 French francs (or equivalent currencies in the Latin Monetary Union), 20.43 German Marks or 24.02 Austro-Hungarian Krones. Discussions took place following the International Monetary Conference of 1867 in Parisconcerning the possibility of the UK joining the Latin Monetary Union, and a Royal Commission on International Coinage examined the issues, resulting in a decision against joining monetary union.

The gold standard was suspended at the outbreak of the war in 1914, with Bank of England and Treasury notes becoming legal tender. Prior to World War I, the United Kingdom had one of the world's strongest economies, holding 40% of the world's overseas investments. However, by the end of the war the country owed £850 million (£30.7 billion as of 2011)., mostly to the United States, with interest costing the country some 40% of all government spending. In an attempt to resume stability, a variation on the gold standard was reintroduced in 1925, under which the currency was fixed to gold at its pre-war peg, although people were only able to exchange their currency for gold bullion, rather than for coins. This was abandoned on 21 September 1931, during the Great Depression, and sterling suffered an initial devaluation of some 25%.

Use in the Empire

Sterling circulated in much of the British Empire. In some parts, it was used alongside local currencies. For example, the gold sovereign was legal tender in Canada despite the use of the Canadian dollar. Several colonies and dominions adopted the pound as their own currency. These included Australia, Barbados, British West Africa, Cyprus, Fiji, Irish Free State,Jamaica, New Zealand, South Africa and Southern Rhodesia. Some of these retained parity with sterling throughout their existence (e.g. the South African pound), whilst others deviated from parity after the end of the gold standard (e.g. the Australian pound). These currencies and others tied to sterling constituted the Sterling Area.

Bretton Woods

In 1940, an agreement with the U.S.A. pegged the pound to the U.S. dollar at a rate of £1 = $4.03. This rate was maintained through the Second World War and became part of theBretton Woods system which governed post-war exchange rates. Under continuing economic pressure, and despite months of denials that it would do so, on 19 September 1949 the government devalued the pound by 30.5% to $2.80. The move prompted several other currencies to be devalued against the dollar.

In the mid-1960s, the pound came under renewed pressure since the exchange rate against the dollar was considered too high. In the summer of 1966, with the value of the pound falling in the currency markets, exchange controls were tightened by the Wilson government. Among the measures, tourists were banned from taking more than £50 out of the country, until the restriction was lifted in 1979. The pound was eventually devalued by 14.3% to $2.40 on 18 November 1967.

Decimalisation

On 15 February 1971, the UK decimalised, replacing the shilling and penny with a single subdivision, the new penny. The word "new" was omitted from coins after 1981.

Free-floating pound

With the breakdown of the Bretton Woods system, the pound floated from August 1971 onwards. It at first appreciated a little, rising to almost $2.65 in March 1972, from 2.42 when it had been fixed. The Sterling Area effectively ended at this time when the majority of its members also chose to float freely against the pound and the dollar.