This "flexible flat" is on the ground floor, actually about four feet below ground level so that the lawn outside comes up to the windowsills.  It's built around a big living room (the central diamond on the plan).  On two sides of the living room, bedrooms hide behind bookcase walls.  But if you're having a party, one or both bedrooms can quickly be turned into extensions of the living room:  just roll the bed into its slot beneath the lawn and swing the bookcases open.