Phil visits the beautiful Houghton Hall in Norfolk, built by Britain's first Prime Minister, the wily Sir Robert Walpole. Phil is keener than ever to uncover the building costs, because they were Sir Robert's best kept secret. As guest of its current owner, Lord David Cholmondeley, Phil uncovers a house clearly built without any limit on costs: It features some of the finest carved stone interiors ever created, jaw-dropping bedrooms, 'beer taps' in a marble dining room, and the most extravagant thing Phil has ever seen: a 17ft silver embroidered bed. It's no wonder Sir Robert wanted to keep the costs - and how he raised the money - a secret; the truth could have rocked Parliament.