Gaggenau Kitchen

Having a health club, resident's wine cellar and screening room with general-release movies helps push prices into the 3,000 pounds-a-square-foot bracket. Add 500 pounds for a limousine service, a Gaggenau kitchen and a squash court.

Top-end lavishness, starting at 4,000 pounds a square foot, will be in an iconic building designed by a famous architect, such as Piano's Shard skyscraper in London, according to Knight Frank. It will include a top international hotel brand and spa operator, stores and restaurants. A white-glove doorman will serve at the internationally recognized address.

"You don't know what you want until you're offered it," Miles-Brown said.

The 72-story Shard will have about 12 apartments on floors 53 to 65. The tower will also have restaurants and offices as well as hotel rooms operated by Shangri-La Asia Ltd., Asia's biggest luxury hotelier by market value. The building is under construction in south London's Southwark neighborhood and apartments aren't yet being offered for sale.

Improved Outlook

Luxury properties in the city costing an average of 3.7 million pounds rose 8.1 percent in June from a year earlier, Knight Frank said last week, pushing its Prime Central London Index to a record. That prompted the broker to predict a gain of 9 percent for the whole of the year, up from an earlier forecast of 3 percent.

London has luxury-home developments valued at about 21 billion pounds in the pipeline, EC Harris LLP said yesterday. Investors and developers plan to build 9,000 prime apartments and houses by the end of the decade, according to the consulting firm, which is based in the city.

Rising demand is extending the upper end of the housing market beyond the central districts. Three penthouse apartments at Barratt Development Plc's Putney Square development were the first to sell for more than 1,000 pounds a square foot outside of the city center, said Gary Patrick, regional sales director at the London-based company.

Barratt, the U.K.'s largest homebuilder by volume, sold the penthouse apartments overlooking communal gardens for about 1,100 pounds a square foot compared with an average of 730 pounds a square foot for the other 157 units on the site.