By 1768, Cox & Drummond were flourishing, with a turnover of £345,000 per annum. During the 1770s the company continued to grow, aided by war in the American Colonies and the threat of invasion from France. Cox repeated his good fortune with business partners, taking in Mr Mair upon Drummond's death in 1772, followed by his own son Richard Bethell Cox in 1779 and then Mr Greenwood in 1783. It was during this time that the company expanded its banking interests, offering loans and accounts to exclusive members of London's elite. Frederick, Duke of York, introduced Cox's business partner Greenwood to his father George III, as "Mr Greenwood, the gentlemen who keep my money". Greenwood replied rather cheekily that, "I think it is rather his Royal Highness who keeps my money", to which George III burst out in laughter and said, "Do you hear that Frederick? Do you hear that? You are the gentleman who keeps Mr Greenwood's money!"