In 2010, Claire Farrow and Ian Hogarth built a home containing a sauna, spa, dance floor and DJ booth on a small patch of land in London. It was a notorious project, with several setbacks - including their digger smashing into a neighbour's wall and the re-emergence of the old river under the building, which threatened to prevent them completing the project. Kevin McCloud revisits the couple to see how they are getting on two years later.