House extension

The four-storey London mansion hidden almost entirely underground: 15 bedrooms, 7 bathrooms, 20 toilets, a ballroom, a pool… and neighbours in uproar
David Graham’s home will feature 14-metre swimming pool and ballroom
Three-storey basement extension will be deeper than height of neighbouring houses and will treble size of the current Knightsbridge property
Novelist Edna O’Brien and other wealthy locals furious at plans

Daily Mail story here