Baroness Thatcher of Kesteven character jug produced by Bairstow Manor Pottery of Hanley, England, circa 2020. Margaret Hilda Thatcher (1925-2013) was Prime Minister of the United Kingdom from 1979 to 1990 and Leader of the Conservative Party from 1975 to 1990. She was the first female British prime minister and the longest-serving British prime minister of the 20th century. As prime minister, she implemented economic policies that became known as Thatcherism. A Soviet journalist dubbed her the "Iron Lady", a nickname that became associated with her uncompromising politics and leadership style. This character jug depicts Thatcher as the Lady Companion of the Order of the Garter and was modeled by Ray Noble.