I would highly recommend booking a stay at Ollie's flat in Knightsbridge. The location is really fantastic - in the middle of one of the nicest/quietest parts of Knightsbridge and yet just a stone's throw away from Harrods, The Serpentine, The V&A etc. The flat would accommodate three quite comfortably. It is clean, quiet, and has wifi and a (large) TV. The biggest plus was Ollie; he was incredibly helpful, maintained good communication throughout and was a delight.