The Royal Mint, from the Tower of London to Llantrisant

The Royal Mint is one of the oldest continuously operating organisations in the country, with a documented history running back to the late Saxon period and a claim to origins earlier still. For a collector the interesting part is narrower: the Mint has had three homes in the period that produced the gold coins actually in circulation among collectors today, and each move changed what the coins look like.

The Tower, 1279 to 1810

In 1279 Edward I consolidated the scattered mints of the kingdom into a single operation inside the Tower of London. It stayed there for more than five centuries, occupying a narrow strip of ground between the inner and outer curtain walls that became known, unimaginatively, as Mint Street.

Conditions were cramped and the work was manual. Coins were struck by hammer until the middle of the seventeenth century, when screw presses driven by teams of men were introduced under Charles II. That change is the reason coins from the 1660s onward are noticeably rounder and more consistent than what came before, and it is also when the milled edge appeared as an anti clipping measure.

The gold coins of this period are the ones most collectors encounter only in auction catalogues: unites, laurels, broads and, from 1663, the guinea. The guinea took its name from the Guinea coast in West Africa, the source of much of the gold, and early examples carry the elephant or elephant and castle mark of the Royal African Company beneath the bust.

Newton takes charge

Isaac Newton was appointed Warden of the Mint in 1696 and became Master in 1699, holding the post until his death in 1727. The role was widely regarded as a sinecure. Newton did not treat it as one.

He arrived in the middle of the Great Recoinage of 1696, an emergency operation to replace the country's clipped and debased hammered silver with milled coin. He reorganised the process, tightened the assay, and pursued counterfeiters personally, gathering evidence in taverns and prosecuting cases through the courts.

His most consequential act was arithmetic. In 1717 Newton set the value of the guinea at twenty one shillings, a rate that overvalued gold against silver and quietly drove silver out of circulation. Britain drifted onto a de facto gold standard as a result, decades before it was formally adopted in 1821.

Tower Hill and the age of steam

By the end of the eighteenth century the Tower site could not keep up. The answer was a purpose built factory on Tower Hill, a few hundred yards away, equipped with steam powered presses supplied by Matthew Boulton and James Watt. The Mint moved across between 1809 and 1812.

This is the address that matters most to anyone collecting British gold. The Great Recoinage of 1816 to 1817, which introduced the modern sovereign, was carried out here. So was Benedetto Pistrucci's Saint George and the dragon, engraved in 1817 and still in use today. So were the Victorian shield and Jubilee head sovereigns, the Edward VII and George V issues, and the 1957 restart that brought sovereign production back after a forty year gap.

Tower Hill also administered the branch mints. Between 1855 and 1932 sovereigns were struck in Sydney, Melbourne, Perth, Ottawa, Bombay and Pretoria, each marked with a single letter, while London output carried no mark at all.

Llantrisant, 1968 to now

Decimalisation ended Tower Hill. Replacing the entire circulating coinage of the United Kingdom required a volume of production the site could not physically accommodate, so a new plant was built on a greenfield site at Llantrisant in South Wales. It was opened in December 1968 and struck decimal coin for three years before the changeover in 1971.

Production was transferred in stages and Tower Hill struck its last coin in 1975. Everything since has come from Llantrisant: circulating coinage, bullion Britannias and sovereigns, the commemorative programme and the Great Engravers series.

Why the address matters to a collector

• A sovereign with no mint mark was struck in London, at the Tower or at Tower Hill depending on the date, and not at a branch mint.
• A sovereign carrying S, M, P, C, I or SA came from Sydney, Melbourne, Perth, Ottawa, Bombay or Pretoria respectively.
• Anything struck after 1975 came from Llantrisant, so the branch mint question does not arise and no mark should be expected.
• Modern listings that say Royal Mint mean Llantrisant, and the phrase carries no information about scarcity on its own.

The Mint's own museum holds the trial plates, the dies and a substantial part of the record, and the Llantrisant site runs public tours. For anything specific about a particular issue, the published mintage figures and the grading service population reports will tell you more than the phrase Royal Mint on a listing ever will.