Last week I had the great privilege to be invited by the Prime Warden of the Worshipful Company of Goldsmiths to the Trial of the Pyx. The Trial of the Pyx is a procedure for ensuring that newly minted coins conform to required standards. It is a judicial ceremony dating back to the twelfth century and is one of the oldest such ceremonies in the world. Trials are held annually and they are trials in the full judicial sense presided over by a senior judge with an expert jury of assayers.

The name Pyx refers to the chests in which the coins are transported, and derives from the Pyx chamber in Westminster Abbey where historically the chests were kept. Little has changed in the procedure since the reign of Henry III; throughout the year, coins are randomly selected from every batch of each denomination struck, sealed in bags containing 50 coins each, and locked away in the Pyx boxes for testing at the Trial.

The Trials used to take place at the Palace of Westminster but from 1870 they have been held at Goldsmiths’ Hall where the Assay Office is situated. The presiding judge is the Queen’s Remembrancer, the Senior Master of the Queen’s Bench, the oldest judicial office in the country, also dating back to the twelfth century. It is his or her responsibility to ensure that the Trial be held in accordance with the law and to deliver the jury’s final verdict to Her Majesty’s Treasury.

Coins to be tested are drawn from the regular production of the Royal Mint. The Deputy Master of the Mint must, throughout the year, randomly select several thousand sample coins and place them aside for trial. These must be in a certain fixed proportion to the number of coins produced. For example, for every 5,000 bimetallic coins issued, one must be set aside, whereas for silver Maundy money the proportion is one in 150.

The jury is composed of at least six assayers from the Company of Goldsmiths together with other members who are leaders in the financial world.  They have two months to test the provided coins, and decide whether they have been properly minted. The benchmark against which the coins are tested is called a Trial Plate. Trial Plates are held by the National Measurement and Regulation Office. Criteria are given for diameter, chemical composition and weight for each class of coinage. The oldest surviving Trial Plate, now preserved in the Royal Mint Museum, is of silver, dating from 1279.

The delivery of the verdict is usually given at this time of year in the presence of the Master of the Royal Mint, who is today the Chancellor of the Exchequer, or his deputy. On this occasion it was indeed George Osborne.

We were received firstly with fine champagne and then summoned into the chamber where the verdict would be given. We were reminded that it was indeed a Court of Law and to switch off our mobile phones but we were permitted to keep our champagne glasses. The officers filed in and took their places. The Remembrancer, Master Barbara Fontaine, the first female holder of the post, then called on the Clerk to the Goldsmiths to deliver the Jury’s verdict. In appropriately sombre terms Sir David Reddaway, the new Clerk to the Goldsmiths read out the verdict, coming to the key phrase that the jury had found that on the whole the coinage was good and true. The Remembrancer confirmed the verdict and then delivered a fine and witty speech linking Shakespeare to the development of trade and commerce.

But what if the verdict had gone against the Master of the Mint? Well, back in the mists of time this was a heinous and not uncommon crime with the most terrible penalties. Given the enormous quantity of coin that was minted before the advent of paper money, and then electronic money, shaving a fraction of sliver off the weight or substituting a tiny proportion of base metal to replace the silver or gold could make a corrupt Master of the Mint a fortune and many were tempted. The penalty if convicted was to be hung, drawn and quartered, the most severe form of execution proscribed under English law.

One of the most celebrated Masters of the Mint was the scientist and philosopher Sir Isaac Newton. Newton was regarded as one of the most distinguished men of his time and a grateful nation wanted to reward him. The idea was to find him a suitable sinecure with a healthy stipend. At first his friends tried to get him a post as a head of one of Cambridge’s colleges. But at that time you had to be a man of the cloth to hold such a post. Them they hit on the Mint. Isaac Newton was appointed Warden of the Royal Mint in 1696 on the recommendation of Charles Montague, Chancellor of the Exchequer. The Royal Mint was then in the Tower of London. It was a time of great activity, for the Royal Mint was grappling with the recoinage of old silver coins dating back to the reign of Elizabeth I and beyond. The enormous operation was completed in three years and then Newton turned to his main duty of investigating and bringing to justice those who clipped and counterfeited the coin of the realm.

While his friends had expected him to take it easy he threw himself into the role with energy and enthusiasm, remaining there until his death in 1727, surviving the political upheavals of these troubled times. He is known to have himself conducted interviews with criminals and informers. His famous report of 1717 paved the way for a reduction in the value of the guinea to the familiar 21 shillings. He supervised experiments on the purity of copper and may even have carried out his own assays of gold and silver. He had a great concern for accuracy and wanted coins to be made of the correct weight and fitness with minimal variation. Newton claimed that he had brought the coinage to a ‘much greater degree of accuracy than ever was known before’. In these circumstances it is no wonder that he reacted angrily in 1710 to the mistaken judgement of the jury at the Trial of the Pyx that his gold coins were below standard.

By coincidence I had only recently finished the great fictional trilogy The Baroque Cycle by Neal Stephenson. In the third book, The System of the World, Jack Shaftoe raids the Tower of London specifically to tamper with the Pyx. Viscount Bolingbroke and Charles White use the event as leverage for political attack against Isaac Newton and his fellow Natural Philosophers.

After the Trial the Goldsmiths gave us an excellent lunch in their magnificent Hall. It is customary to avoid political discourse but in his speech the Prime Warden did refer to Brexit. But he managed to steer skilfully through the Scylla and Charybdis of these choppy waters by telling us that he had renamed the family dogs, Boffin and Brexit. The older, more conservative pooch was now called Boffin, short for B-etter OFF IN while the younger, more impetuous mutt was named Brexit. The Prime Warden managed to avoid giving away his personal voting intention but as the scion of the Schroder family we might be able to guess. In his reply the Chancellor also avoided direct political comment but managed to get in some digs at his political opponents. He showed us a new kilogram gold bar which is now on sale. He told us its price and said that if he sold some 17,456 of these he would have sold as much gold as a certain predecessor. And referring to the forthcoming anniversary of the Great Fire he thought that that had probably done as much damage to London as the cycle lanes of today!

Uniquely perhaps among the Great Twelve Livery Companies the Goldsmiths have retained their central purpose of monitoring the quality standards of precious metals right up to the present day. The others have largely morphed into institutions primarily of philanthropic purpose. Some companies have successfully reinvented themselves, famously like the fanmakers who after the decline of ladies’ fans deliberately sought to recruit those who use fans in engineering as in aeroplane engines or air-conditioning. But the Goldsmiths are still Goldsmiths.