Downing Street (London) ... Prime Minister of the United Kingdom, and the Second Lord of the Treasury, an office held by the Chancellor of the Exchequer. The most famous address in Downing Street is 10 Downing Street, the official residence of the First Lord of the Treasury—and thus, in modern times, the residence of the Prime Minister, since the two roles have been filled by the same person. As a result of this "Downing Street" or "Number 10" is often used as short-hand for the Prime Minister or their office, whilst "Number 11" is likewise a term for the Chancellor of the Exchequer or their office. Downing Street is located in Whitehall in central London, a few minutes' walk from the Houses of Parliament and on the edge of the grounds of Buckingham Palace. The street was built by and named after Sir George Downing, 1st Baronet (1632–1689). Downing was a soldier and diplomat who served under Oliver Cromwell and King Charles II. In the service of the King he was rewarded with the plot of land adjoining St. James's Park upon which Downing Street now stands. The Prime Minister, the Chancellor of the Exchequer, and the Chief Whip all officially live in houses on one side of the street. The houses on the other side were all replaced by the massive Foreign Office in the nineteenth century. In the 1950s and 1960s, plans were considered to demolish both the Foreign Office and the rest of Downing Street and build "something more modern". However the plans were never implemented and have long since been abandoned.