Boulton founded the Soho Mint, to which he soon adapted steam power. He sought to improve the poor state of Britain's coinage, and after several years of effort obtained a contract in 1797 to produce the first British copper coinage in a quarter century. His "cartwheel" pieces were well-designed and difficult to counterfeit, and included the first striking of the large copper British penny, which continued to be coined until decimalisation in 1971. He retired in 1800, though continuing to run his mint, and died in 1809. His image appears alongside his partner James Watt on the Bank of England's current Series F £50 note.