Clouds sail over the distant hills like galleons as a storm builds. Dennis Pedersen and Misia Godebska can keep a weather eye on the countryside for miles around from high above the treetops. For while some convert barns or tart up tumbledown cottages, the couple had far loftier ambitions when it came to their dream home. Six years ago, they bought a rusting water tower on the edge of Castle Acre, near Swaffham, for £25,000