the sprawling house , west london , has been sold for 300 times the average price of home in england and wales .
but the house is 18 times the size of the average new home , with nine bedrooms , nine bathrooms , a japanese water garden and an indoor swimming pool .
the owner , who commissioned the mansion , had put the house on the site of an old telephone exchange in chelsea , west london .
it has now been bought by an offshore company for £ 51,191,950 , according to land registry figures .