"It's as wonderful as I could ever have imagined," says Mackintosh. "It's because of the people who built it. There aren't many houses that are made with that kind of care. What I love is that everyone who comes into the house says that it feels like it's always been here. Everybody."

He has pulled it off. Done badly, such a house would be a disaster - the worst kind of unthinking historical pastiche. But this is different: the first real Arts and Crafts house of the 21st century. At no point does it feel forced or - for all its owner's occupation - over-theatrical. It just feels comfortable, natural, something that has arrived in the landscape by some organic process. This is for two reasons. First, there is no big-name architect or fashionable interior designer involved: the design was genuinely collaborative, though everybody knows who the boss is. Secondly, Mackintosh has brought a huge amount of his own life and family history into the project, and directed it with an exacting eye for detail. If this house was a musical, it would run and run.