In what may well be the most expensive apartment in the world, a 16,000 square foot residence in London’s opulent Knightsbridge has just been sold for €170 million. And that’s unfurnished.

It’s unlikely the new owners will be shopping in Ikea however; this is after all fast becoming an unsustainably expensive corner of the English capital, buoyed by Russian oligarchs, Chinese tycoons and Arab sheikhs.

London has now become one of the most expensive markets in the world leading to increasing fears ordinary residents are being squeezed out.

Property consultant Savills calculates that ten of the city’s boroughs now have an aggregate property value equivalent to the total of Scotland, Wales and Northern Ireland combined.

The super-luxurious One Hyde Park development in Knightsbridge, the site of this most recent and ostentatious penthouse sale, is seen by some as part of the problem.

“We’re in boom-time prices, more expensive than we’ve ever been in the history of mankind,” said Nick Candy, one of the developers.

Not much is known about the new owner although he or she is believed to be of Eastern European origin. The final furnished product could be worth as much as €213 million, according to developers CPC Group.

Reports from the development’s launch in 2011 sited a valet, wine cellar, private spa and a panic room as part of what appeals to the world’s financial elite.

Britain’s previous record for an apartment was set three years ago by Ukrainian billionaire Rinat Akhemtov, who paid €166 million pounds for a penthouse and apartment in the same block to knock together into one property.

To date there have been around €1.5 billion in sales at the tower, whose developer is a joint venture between CPC Group and Waterknights, the private company of Qatar’s Sheikh Hamad Bin Jassim Bin Jabor Al Thani.

Candy & Candy, run by Nick Candy, were the interior designers and development managers.

Luxury London prices have soared by almost 80 per cent since 2009, and while such abodes, untouchable to the ordinary man, grab the headlines, prices have rocketed even in more downmarket areas.

According to Savills prime central real estate values have risen 79.4 per cent since March 2009, against a 40.6 per cent increase in greater London house prices over the same period.

“There is a concern over the market overheating,” warned Mr Candy.

“Everyone thinks the main central London is doing so well, (so) the ripple effect is going throughout the UK, and some of the prices being achieved are probably unrealistic and not sustainable.”