<P> It currently houses the UK Cabinet Room in which Cabinet meetings in the UK take place, chaired by 10 Downing Street resident Prime Minister Theresa May . It also houses the Prime Minister's executive Office which deals with logistics and diplomacy concerning the government of the United Kingdom </P> <P> Number 10 Downing Street was originally three properties: a mansion overlooking St James's Park called "the House at the Back", a town house behind it and a cottage . The town house, from which the modern building gets its name, was one of several built by Sir George Downing between 1682 and 1684 . </P> <P> Downing, a notorious spy for Oliver Cromwell and later Charles II, invested in property and acquired considerable wealth . In 1654, he purchased the lease on land south of St James's Park, adjacent to the House at the Back within walking distance of parliament . Downing planned to build a row of terraced town houses "for persons of good quality to inhabit in ..." The street on which he built them now bears his name, and the largest became part of Number 10 Downing Street . </P> <P> Straightforward as the investment seemed, it proved otherwise . The Hampden family had a lease on the land that they refused to relinquish . Downing fought their claim, but failed and had to wait thirty years before he could build . When the Hampden lease expired, Downing received permission to build on land further west to take advantage of more recent property developments . The new warrant issued in 1682 reads: "Sir George Downing...(is authorised) to build new and more houses...subject to the proviso that it be not built any nearer than 14 feet of the wall of the said Park at the West end thereof". Between 1682 and 1684, Downing built a cul - de-sac of two - storey town houses with coach - houses, stables and views of St James's Park . Over the years, the addresses changed several times . In 1787 Number 5 became "Number 10". </P>

Why is number 10 downing street the home of the pm