In 1279 the number of mints in England was reduced, and a unified system was established, run from the London mint. Thereafter, only a few local and episcopal mints continued to operate intermittently, and by 1553 English minting was wholly concentrated in a single establishment. Thenceforward, save during the Civil War and the existence of temporary country mints during the recoinage of the 1690s, one mint served England, Wales and Ireland. From 1710 it also served Scotland since, following the Act of Union which provided for coin of the same standard and value throughout the United Kingdom, the Edinburgh mint closed on 4 August that year, though it was not formally abolished until 1817. The Royal Mint worked independently until control by the Treasury was established after 1688.
Nothing is known of the administrative control of the Mint before the reorganisation in 1279; but both before and after that date control of currency policy was vested in the monarch until as a result of the 1688 Revolution it passed from the crown to Parliament.
The organisation as established in 1279 endured in form until the nineteenth century. At first the warden was the monarch's immediate representative in the Mint, and all coin or bullion reached the Mint through him. He was constituted a magistrate and judge for all matters affecting the Mint and it was his duty to act against counterfeiters or clippers of coin. He also collected the dues of the Mint and defrayed and accounted for its expenditure until, under the Coinage Act 1666, the master, first appointed in 1278, replaced the warden as the effective head of the Mint. From 1680 to 1686 the office of master was executed by a Mint Commission. In 1787 a Committee of the Privy Council on Coin was set up as a result of the parlous state of the currency and alleged negligence of masters of the Mint. Its membership was widened in 1798 and for the following 16 years this body assumed the major responsibility for Mint administration. It was wound up in 1816 but its recommendations led to the recoinage and reorganisation of the Mint after the Napoleonic Wars. The comptroller, also an office dating from the thirteenth century, administered building work and miscellaneous services. Any fresh expenditure was discussed by these three officers as a board. In the eighteenth century the use of deputies, first employed in the fifteenth century, was applied to all posts, management passing entirely to the deputy master. The warden ceased to take much part in business even by deputy, and his post was abolished in 1817, the title subsequently passing to the master. Many important duties were performed by contract, notably the manufacture of coinage which was undertaken by the Company of Moneyers.
From early in George III's reign to the mid-nineteenth century the mastership was a political appointment, often held by a Cabinet minister, sometimes in conjunction with another office. In the reorganisation of the Mint after the Napoleonic Wars deputising was abolished for all posts save that of master and the Mint Board was expanded. Another reorganisation in 1851, following the recommendations of a Royal Commission on the Mint appointed in 1848, removed the mastership from the political sphere. Its holder became a permanent official discharging his duties in person with authority over the whole staff, and assisted by a deputy master. The contractual system of coinage was ended and the Mint Board was dissolved, and by an order in Council of 7 March 1851 future regulation of the establishment was committed to Treasury minute. In 1870 the mastership was vested in the office of the chancellor of the Exchequer, though with power to discharge all duties by deputy. Since then the deputy master, whose office was merged with that of the comptroller in 1854, has been the administrative head of the Mint, appointed by the Treasury. The internal structure of the Mint was also thoroughly reorganised in 1870 into three main divisions: the Mint Office, the Assay Department, and the Operative Department, formed by an amalgamation of the Coining and Die and Melting Departments.
The main, and for much of its history the sole, function of the Royal Mint has been the production and care of the home coinage. During the last hundred years its work has spread to include coinage of many Commonwealth and other countries. Silver remained the fundamental measure until gold took over that function in the eighteenth century, after which silver coinage dwindled into a token currency in the nineteenth century, finally being replaced by cupro-nickel under the Coinage Act 1946. The Mint's major preoccupation until the First World War was then the maintenance of the gold circulation which was as much a world as a national currency. Gold coinage ceased in 1917, and bank notes, first introduced in 1694, then became the principal money, all coins being tokens of negligible intrinsic value.
At various times the Mint has performed other duties. Today its work includes the manufacture of medals and seals and of a considerable range of machinery. It is the guardian throughout the United Kingdom of the standard of all hall-marking of articles of bullion by bodies other than the Goldsmiths' Company. Early in the reign of Queen Anne, the Government contracted with the Parliament of the Stannaries to buy 1,600 tons of their tin annually for seven years at £70 per ton, and the Mint undertook the storage and disposal of the tin. At the end of the seven years, the contract was renewed for a further seven years, with an obligation to increase the annual quantity to 1,800 tons. Upon the death of Queen Anne, the Mint was relieved of the tin business by the transfer of the Duchy of Cornwall and the problem of marketing the tin to the Prince of Wales. The Mint was also responsible for devising and producing dies for stamping the duty on taxed papers. In 1910 it took over the production of the plates for printing all postage and revenue stamps, and at the same time that of dies for impressing a revenue stamp on cheques, transfers and legal documents. The printing of plates for National Health and National Insurance stamps followed in 1911 on the passing of these acts. Other duties subsequently acquired were the production of plates for printing passports for the Foreign Office, of medicine duty labels for the Board of Customs and Excise, and of other security documents.