So Mr. Lockwood, the unfortunate builder of this modern monstrosity, gets his Sales Manager, Nigel Pitt, to pretend to be the current owner in order to make a more effective 'sell' to the first prospective buyers in years. To give an additional touch of authenticity he engages an actress to play the part of Nigel's wife, just while Sir Lindsay and Lady Cooper have their look round. But the real complications start when the Coopers are fogbound and have to stay the night-and turn out not to be husband and wife at all. From here on the permutations become so intricate that it seems impossible the authors can ever sort them out. But miraculously they do, so hilariously that one can easily understand why audiences kept rolling up to the Whitehall to see this play for such a long time.