Exclusive, extraordinary and for sale. There are the homes that just have to be seen - so we've hunted them down for a fascinating and very private view.
This week: The Rotunda, Bushy Park, Hampton, Richmond
What: Set within Richmond's glorious Bushy Park, this former torpedo testing tank has been converted into a £4million luxury home.
We say: It wouldn't be top of everyone's wish-list, but this must certainly be one of the most unique properties currently on the market. Designed to curl around four-foot thick blast-proof concrete walls, the Rotunda is a seven-bed seven-bath former laboratory, which, as well as being an award-winning building, also played an important role in the development of Cold War defence technology.
The Rotunda was originally constructed in the 1950s by the Admiralty as a vast domed tank where torpedoes would be rotated at the end of a metal arm. The site, including the Georgian manor house next door, The Upper Lodge, had been used for military purposes during WW2 when the park was taken over as a centre for planning D-Day because General Dwight Eisenhower did not want to work in the centre of London.
Following the war, the Ministry of Defence held onto the site and it became part of the Admiralty Research Laboratory, which tested mines in one of the ponds, now the recently restored Bushy Park Water Gardens.
If the building's stark modernity and unusual past seems a little incongruous among the thousand mature acres and roaming deer of Royal Park, it could be because it's located in the wrong place.
It was commonly believed by those stationed at the camp that the base was originally intended to be at Bushey in Hertfordshire, and was built in Bushy Park due to a misunderstanding by the Americans.
Fast forward to 2004, when the Rotunda was converted into a very contemporary 10,000 square foot modernist home, with an abundance of glass and steel under a copper roof, which won its architects a design award.
The original dome has been removed, with the former pool area made into gardens, and the stretch of curved concrete wall used to form the backbone of the first two floors.
Internally there is a 95ft-long open-plan reception and kitchen/dining room running almost the full length of the house, and upstairs the seven bedrooms and bathrooms, as well as a dressing room and terrace, jigsaw neatly into the curve.
If that sounds a bit cramped, don't worry, there is more. To use the well-worn phrase, this house really is deceptively spacious as it comes with two additional levels of subterranean space that have not yet been converted.
Luke Ellwood, partner at Knight Frank's Richmond office, who is marketing the property says, "The underground space has great potential.
"It would make amazing leisure complex, with an underground swimming pool, gym, spa and sporting facilities, which could appeal, for example, to a footballer. We've also had interest from musicians who can see the potential for studios."
And the location is also likely to make the Rotunda appeal to the glitterati. "It has a very secluded plot of 1.3 acres set within the unique location of the Royal Park, and it offers a very good degree of security for someone who wants to be able to get away from it all."
Not that the Rotunda is isolated. It sits next to the Upper Lodge, also sold recently by Knight Frank to a British buyer for close to the £8.85 million asking price.
Although he's obviously a fan, Ellwood admits that houses like the Rotunda won't have mass appeal. "The building is unusual, and it's certainly very different from the others in the park which are large period houses.
"It doesn't fit the conventional market, and with these properties you have to market to a wide audience; developers, the local and the international market. But being unusual won't affect the price. You just have to wait for the right buyer.
"It's a unique property, with substantial accommodation in the most amazing surroundings, and the right buyer, looking for something individual, will be prepared to pay a premium."
To use the well-worn phrase, this house really is deceptively spacious as it comes with two additional levels of subterranean space that have not yet been converted.