Newton ran the Royal Mint and had forgers executed

In 1696, Newton was appointed warden of the Royal Mint, which was in charge of manufacturing England's currency. He left Cambridge, his long-time home, and relocated to London, where the mint was housed in the Tower of London. Newton was promoted to the more lucrative position of master of the mint three years later, a position he held until his death in 1727.

Newton oversaw a massive campaign to remove all of the country's old coins from circulation and replace them with more stable coinage during his term at the mint. He was particularly interested in researching counterfeiters, and as a result, he became acquainted with the city's murky underbelly as he personally tracked down and questioned suspected criminals, receiving death threats in the process. Several of the forgers he went after were hanged.