A 'perfect' mansion which has been sold for £51million in an exclusive part of London has become one of the UK's most expensive  homes - and the buyer also has to pay £7.6m in stamp duty. The sprawling house, built on the site of an old telephone exchange in Chelsea, west London, has been sold for 300 times the average price of home in England and Wales. But the stamp duty alone, paid on top of the price of the home, is enough for the Treasury to pay the annual salary of 330 nurses. This sprawling house, built on the site of an old telephone exchange in Chelsea, west London, has been sold for 300 times the average price of home in England and Wales . The transaction means it is one of the most expensive homes to ever sell in the UK. Spread across four floors, the house is 18 times the size of the average new home, with nine bedrooms, nine bathrooms, a cinema, a Japanese water garden and an indoor swimming pool. The owner, who commissioned the mansion, had put the house on the market for £55 million. It has now been bought by an offshore company  for £51,191,950, according to Land Registry figures. A spokesman for Knight Frank, which sold the home, would not comment further. The property is situated on Boltons Place, at the top of The Boltons, an exclusive street made up of late 19th and early 20th Century mansions. The huge tax bill, the equivalent to 15 per cent, is down to the buyer using a Bermuda-based company to buy the property. Under the Annual Tax on Enveloped Dwellings (ATED), which is payable by companies that own UK residential property, there is a further bill of £218,200 each year. The property has now been bought by an offshore company for £51,191,950, according to Land Registry figures . Spread across four floors, the house (pictured left) is 18 times the size of the average new home, with nine bedrooms, nine bathrooms, a cinema, a Japanese water garden and an indoor swimming pool . Knight Frank's Knightsbridge office had previously described the property as an 'exceptional detached recently built mansion' which was 'presented in immaculate condition throughout'. The advert said: 'The intention from the outset was to bring together the very best in the fields of construction and building services together with the most accomplished artisans and craftsmen to create and build the perfect house. 'Only materials of the highest quality have been employed by the most skilled workmen in order to create a house of unparalleled and exacting design.' The 17,500 sq ft house was built on the site of an old BT telephone exchange, which three developers bought for £15million in 2002. Estate agents Knight Frank's previously described the property as an 'exceptional detached recently built mansion' which was 'presented in immaculate condition throughout' They then demolished the building and commissioned architects Barrett Lloyd Davis to design three mansions. The properties, which were built by Walter Lilly & Company and completed in around 2006, feature a double height entrance hall along with glass lift. Simon Barnes, a property consultant, today described it as 'the perfect home'. It was built on top of an old telephone exchange in the upmarket Boltons Place, Chelsea . He said: 'The properties weren't built by developers to sell, they were built for them to live in. 'They are amazing. There is a spacious hallway, very good reception rooms and bathrooms. They are as near a perfect home as you can get. Great for entertaining in, and great for living in. 'In Prime Central London, 99 per cent of these houses are listed or in a conservation area so you can't just rip one down and rebuild it. 'Boltons Place was built on an old telephone exchange. In Prime Central London it is unique. The sale represents great news for the Treasury and the owner has a wonderful new home.' Alex Newall, managing director of Hanover Private Office, described the mansion as 'an awesome space'. He said: 'Boltons Place is well laid out and in a superb location. There are only a handful of homes like this in London. 'The ceilings are four-metres high, there is a massive lift, the master suite takes up a whole floor - it really is an awesome space. 'There is demand, but it is the availability that is the problem. Most streets are listed so it is difficult to find somewhere to build a house like this. A lot of people will keep the facade, but rebuild the house behind it.' Henry Pryor, a buying agent, added: 'Strange though it may seem this property looks good value when you consider what you could pay for flats in one of the posh new developments in Knightsbridge and Mayfair.'
The house sold for 300 times average price of home in England and Wales.
Nine-bed property in Chelsea is 18 times the size of the average new home.
Mansion, marketed for £55m, been bought by  company based in Bermuda.
Stamp duty alone is enough for Treasury to pay year's salary of 330 nurses.