THE lads from The Sweeney wouldn’t believe what’s been going on in their old “manor”. In the heyday of the 1970s detective series there was always a scene where Regan and Carter, played by John Thaw and Dennis Waterman, would be in a car chase, burning rubber as they swerved through a disused warehouse and screeched to a halt in front of a block of lockup garages. Fast-forward three decades and precisely that kind of grim urban backdrop is now the site of one of London’s most ambitious brownfield residential building projects. It’s The Organ Factory in Holland Park, home to Andrew and Sue Lamont.

The transformation of this ruin into a stylish home with its own private art gallery began in late 1999. Andrew, an art dealer, and Sue, an interior designer, were looking for premises in West London where they could live and work under one roof. “We were particularly set on Holland Park,” says Andrew. “It has this exciting, edgy quality. There’s enormous wealth here – Elton John has a house around the corner – but there’s also a council estate near by.” They looked desperately for somewhere suitable, tramping the streets, knocking on doors and inquiring in shops. One day, at a party, someone suggested The Organ Factory.

“I still remember the day we saw it,” says Sue. “It was a burnt-out shell, but it had such height and space. We turned to the estate agent, who’d given up all hopes of selling it, and said: ‘It’s great, we’ll have it.’ He almost fainted.”

The building, which dates from 1872, was just what its name suggested: a factory that had been used for the construction of church organs; later it was a garage. Although indisputably an eyesore, structurally it was sound. The floors were supported on steel underpinnings, to take the weight of the organs, and the outer walls, although bowing in places, were saveable.

The couple had £384,000 from the sale of two business premises in Bethnal Green. In the five weeks before Christmas 1999, when they were due to take a break in Australia, Sue’s country of birth, they worked with their architect, Malcolm Pawley, on plans for the house. It was to be a three-storey construction, built around the gallery as a focal point. “But that alone would have made the house too tall,” says Andrew. “So Pawley had the idea of adding the conservatory to the ground floor, giving us a broader base with more lateral living space.”

Work started early in 2000, and it took only four months to dig foundations, strap the external walls together and install extra windows to flood the old factory with light. It took a further five months for the internal walls and floors to be put in and for the first-fix electrics and plumbing to be completed. There was then a delay until 2002 before planning permission for the conservatory was granted and the project could be finished.

The whole job cost about £900,000 and the end product is dramatic. From the street the property retains its Sweeney look, but the perception changes once you walk through the electric gates of the courtyard and into the home itself. “Modern interiors often look stark and impersonal and we didn’t want that,” says Andrew. “We wanted a soft industrial aesthetic. That meant using materials that are true to the building but colours that make it less harsh.” The drawing room is a mix of classical elegance and industrial chic: chandeliers and period dining chairs stand amid reflective metallised wallpaper and gunmetal-grey windows and doors. The conservatory – Sue’s homage to her native Queensland – has dark slate flooring and oak-clad walls, with rugged chairs and tables crafted from Australian wood.

The art gallery covers 1,500 sq ft. It is a wonderful showpiece, but unlikely to be of use to most buyers. Andrew has therefore drawn up plans to transform it into a family room-cum-library. At the top, above the four bedrooms, is the comfortable living room, a red-painted eyrie with fantastic views over the gallery below.

There must be hundreds of brownfield sites in London, so is this sort of project to be recommended? “Only if you use specialist surveyors and legal advisers,” says Andrew. “You have to understand that you’ll face problems that the average DIY developer will never encounter. What do you do about underground petrol tanks? What about safety? What about contamination of drainage? It’s very expensive and it’s extremely challenging. But it can be done and it’s immensely satisfying.”

The Organ Factory is for sale with Cityscope (020-7830 9776) and Bective Leslie Marsh (020-7221 4805) for £3.95 million

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers