Sir Isaac Newton was the most significant figure of the ‘Scientific Revolution’ of the seventeenth century. His legacy shaped our understanding of mathematics and physics and helped define the modern world. While few people will be unaware of his reputation as a scientist, many do not know that he was Master of the Mint for nearly three decades. He brought his pursuit of precision to his role at The Royal Mint and much of his work had a far-reaching effect on our coinage and the British economy. His meticulous report of 1717, commonly known as ‘the valuation of the guinea’, was pivotal in establishing gold coins as the pre-eminent currency of the United Kingdom. It suggested establishing the gold guinea’s value at 21 shillings which paved the way for the introduction of the Gold Standard a century later.