When it comes to choosing a home, most of us simply scour the property pages, badger estate agents, push for a bigger mortgage and fret over what price to offer. But things were different with Mark and Amelia Wilson. In 2006, coming to the end of careers spent abroad, they bought an Edwardian townhouse in Chelsea for £4.7 million - but not before consulting a blind, septuagenarian feng shui expert in Hong Kong.

“We took the details of five different properties,” Amelia says. “He picked this house, and even told us what price to offer.” To their surprise the offer - which was identical to their bank mortgage valuation - was accepted.

The semi-detached house is in an early 20th-century development around Chelsea Park Gardens, a square near Kings Road. The rooms were badly sub-divided, so they decided on a complete £2 million remodelling. “We wanted to achieve the right balance between contemporary and classical,” the architect, Chris Dyson, says. The building, in a conservation area, appears unaltered from the outside. However, all the windows have been replaced in new oak to match the originals, and are fitted with argon-filled double-glazing to provide sound and heat insulation. External walls and chimneys have been rebuilt or repointed and then aged; reclaimed tiles were used for the roof.

“The biggest job has been to expand the interior space,” Dyson says. “We dug out the basement and raised the roof to enlarge the house from 4,500 sq ft to 6,000 sq ft.” The result is a five-bedroom, five-bathroom home with a high-spec basement service area and a clutch of “trophy” rooms including a mirror-walled gym, a walk-in cold-storage room and an underground seven-seat cinema.

“It's the details that are important,” Amelia says. “And the feng shui.” She points to a circular motif, in American black walnut, on the light oak doors into an attic space. “In feng shui, you use a lot of round shapes to create harmony inside,” she explains.

As we descend the specially constructed cantilevered oak staircase that winds up the five-storey house, they point out the curved, shining walls on each of the stair landings. “They are covered in five layers of hand-polished Stucco Venezia,” says Ian Harper, an interior decorative artist who has also been working on a gold-leaf ceiling in the hall.

Each space comes with its own design and architectural references: the borrowing of light to illuminate darker recesses was inspired by Sir John Soane, for example, and the bronze doorhandles by Arne Jacobsen.

The Eastern elements in the house, recently valued at £12 million, extend to the Zen-inspired garden. Water is pumped across the ribbed black granite wall or trickled into the circular bronze bowl, to calm the spirit and mask the background hum.

chrisdyson.co.uk; ianharper.com

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