the only way is down. But this desire for digging isn't to everyone's liking. Last week a furore erupted when plans were released for a four-storey basement beneath a 19th-century schoolhouse in Knightsbridge, for Canadian former TV mogul David Graham. Tripling the size of the property , this gargantuan pleasure cave would house a ballroom and swimming pool, with hot tub, sauna and massage room, as well as 15 bedrooms, seven bathrooms and 20 toilets, plunging deeper into the earth than the height of neighbouring homes . "These plans are absolutely monstrous and unnecessary," said one neighbour, the Duchess of St Albans. "It's just absolute greed. No one needs that much space. Quite apart from that, the commotion is going to be dreadful." "This is totally out of keeping with the relatively small size of other houses in the area," agreed a spokesman for the nearby Milner Street Area Residents Association. "Why should we all suffer just so one man can indulge his fantasy?" Such fantasies are not restricted to this one man alone. The past five years have seen sprawling underground leisure lairs excavated across west London, from Knightsbridge to Belgravia, Fulham to Notting Hill. They contain playrooms and cinemas, bowling alleys and spas, wine cellars and gun rooms -- and even a two-storey climbing wall. It is leading to a kind of iceberg architecture, a humble mansion on the surface just the visible peak of a gargantuan underworld, with subterranean possibilities only limited by the client's imagination. "Houses