In the aftermath of the Napoleonic Wars (from about 1799 to the Battle of Waterloo in 1815) the British government undertook a revision of the country's money. In 1817 it introduced the sovereign, a 22 carat gold coin worth 20 shillings, which replaced the guinea, which was worth 21 shillings. The new coin was an international success. During the nineteenth century the British gold sovereign became the most secure trading currency in the world. It was given an additional boost with the discovery of gold in Australia in 1855. The coin was designed and engraved by the Italian artist Benedetto Pistrucci (1783-1855), who had come to England in 1815 and been employed at the Royal Mint from 1817. Pistrucci's celebrated design of St George and the Dragon is still used on sovereigns struck at the Royal Mint for collectors.