High Quality Content by WIKIPEDIA articles! Humphrey (c. 1988 – March 2006) was a cat employed as the Chief Mouser to the Cabinet Office at 10 Downing Street, the official residence of the Prime Minister of the United Kingdom, from October 1989 to 13 November 1997. Arriving as a one-year old stray, he served under the premierships of Margaret Thatcher, John Major and Tony Blair, but retired a few months after the Blairs moved in to Downing Street. He was the successor to Wilberforce. He was frequently referred to in jest by the press as an actual employee at Number 10.