Whoever collects the keys to Number 10 later this week will reside in what Margaret Thatcher called "one of the most precious jewels in the national heritage". If you fancy a property with political connections of its own, how about a Belgravia apartment that belonged to Lord Boothby, MP for East Aberdeenshire? Or a Georgian house in Westminster that Home Secretary John Anderson once called home? The following five properties all get our vote.