One of the most popular cats in office was Humphrey, a long-haired black and white stray cat. He worked as a mouser for eight years at 10 Downing Street, the official residence of British premiers. His primary duty was to catch mice and rats. He joined the cabinet office of Prime Minister Margeret Thatcher at the age of one in 1988 and served John Major and Tony Blair, before he retired from his office at 1997.