Michael continues his journeys in greater London. Beginning on its southeastern fringe in the leafy and historic village of Chislehurst, Michael finds surprising imperial connections and a dark labyrinth beneath. Michael discovers that during the years between the wars, a mushroom farm thrived in the 22 miles of man-made passages and tunnels. Once war broke out, however, he finds that the caves became one of the largest public air raid shelters in the land, offering refuge to up to 15,000 people. Next stop is Eltham, boyhood haunt of Henry VIII, who grew up in its grand royal palace. Michael investigates how, in the early 1930s, a wealthy couple rescued it from dereliction and created their own 'grand design' of the day. Stephen and Virginia Courtauld restored the magnificent great hall and added a vast new mansion, which embraced the art deco style and mod cons of the period. Michael marvels at the opulent design and the glamorous cocktail parties hosted by the pair.

• Michael Portillo