It is the perfect London pied-à-terre for a non-dom tycoon about town. A three-storey penthouse overlooking Hyde Park has been sold for £136m – becoming by far the most expensive flat ever bought in Britain.

An unnamed buyer, using lawyers in Ukraine, has bought two apartments in the newly opened One Hyde Park development in Knightsbridge that have been knocked into one to create a 25,000 sq ft (2,300 sq m) penthouse with a wine cellar and access to room service at the neighbouring Mandarin Oriental hotel, according to documents filed last week at the Land Registry.

The price eclipses the value of landmark properties elsewhere in the world. In Beverly Hills, the 3.7 acre Hearst mansion, where John and Jacqueline Kennedy honeymooned, is on the market for just $95m (£58m). And in Manhattan, luxury apartments in the Plaza hotel overlooking Central Park cost a little over $50m.

One Hyde Park has been developed by thirtysomething brothers Nick and Christian Candy, who began their property career with a £6,000 loan from their grandmother, and who have been involved in several other luxury projects, including an aborted scheme to build on the site of London's Chelsea Barracks.

Nick Candy said that 45 flats in the development have sold so far for a total of £963m – an average of £22m each: "No one else has achieved that – not just in London, but anywhere in the world," he said. The £136m sale was agreed several years ago, but has only just been formally documented by the Land Registry. For the same amount, the buyer could have bought 1,564 houses in Burnley, the Lancashire town recently named as Britain's cheapest, with an average property price of £87,194.

The penthouse was purchased as an empty shell, and the buyer is spending £60m fitting it out. Neighbours will be a multicultural bunch – purchasers already identified include the Kazakh copper billionaire Vladimir Kim, the prime minister of Qatar and Irish developer Ray Grehan.

"There's a lot of Indian and Chinese money in London and we're doing a lot of deals with Middle Easterners," said Candy, adding that buyers are investing in London and elsewhere following unrest in nations such as Egypt, Bahrain and Syria. "Because of the turmoil, they need to find a safe place for their money," he said.