IT'S A HOUSE OF TWO HALVES

What does a stylish builder want from his own house? Marcus Field visits Martin Lee, former long-term squatter, now the proud owner of a cool inner-city conversion

At 43, Martin Lee is celebrating the purchase of his first new furniture. "I've always lived with stuff from skips before," says the former long-term squatter and now proud owner of a cool, contemporary- looking conversion of a shop and industrial space in EC1, London. Tall and sharp-looking, with close-cropped hair and a well-cut suit, the successful builder of smart fashion shops and trendy bars recently moved into the space with his two sons, Jakob, eight and Luca seven, and furnished it top to bottom in a suitably groovy style (no coffee-table glossies here, just the Big Issue slung casually on the kitchen worktop). So what prompted this transformation from slumming subversive to new property boom junkie?

"I just wanted to build my own house," is the characteristically uncomplicated response.

Lee started life in a compact Victorian terraced house in Leytonstone, east London. After training as a carpenter, he moved to the West End where he lived for a time in an infamous Huntley Street squat. His career began to take off when he became a builder, and later project manager, for Howard and Constable, the respected contractor for projects like the Issey Miyake store on Brompton Road in Knightsbridge and Sir Terence Conran's restaurant Quaglino's. When that business folded in the recession, Lee set up on his own. Three years and a few high-profile projects later (including a shop for Katharine Hamnett on Sloane Street and the oyster bar at the Stephen Bull Bistro in Smithfield), he had made enough cash to realise his house-building ambitions.

But first he had to find a site. To help with this he engaged Derek Wylie, a 40-year-old architect whose past work includes restaurants, bars and houses - some of them built by Lee. Wylie soon came up with a building ripe for conversion on St John Street, the fault line which separates Clerkenwell's dinky urban village from East London sprawl. Measuring 85ft from front to back, and made up of shop front with a large derelict workshop to the rear, the space came at "a bargain 1995 price" for 4,000sq ft. "It had been used for raves and stuff," remembers Lee. "It was all painted black and purple and there was a dead chicken lying in the space." But to an experienced squatter's eye the potential was clear.

However, before progress could be made, negotiations had to take place with local planners who, because the building is in a conservation area, took a keen interest in the proposed changes. "They wanted a period shop front," says Wylie. "But for me the conservation issue here wasn't about the front, it was about the space inside."

Following this premise, Wylie's approach has been to pare back the layers of accretions inside, leaving the shell of the original buildings complete with scars of former windows and doorways visible in the grit-blasted brickwork. On the footprint of the former shop, he has inserted an office for Lee flanked by entrances to the house and a separate flat above. This home office has proved unexpectedly useful for Lee (a live/work quota was a planning requirement for the site) who enjoys the clear distinction it creates between family life and work.

Beyond the office a floor-lit passage steps down into the voluminous living space which occupies the entire floor area of the old workshop. Daylight floods in from new etched-glass roof lights, brick walls have been whitewashed and a new oak floor laid. "I didn't want it to be too pure or gallery-like," says Lee, eschewing the vogue for polished minimalism prevalent among his clients. Instead, there is a robust, democratic feel (there are no formal rooms or spaces off-limits to the children), which ensures the house is suited to the family's favourite pastime: football in the living room.

Running half the length of the living space is the kitchen, a sci-fi inspired concoction complete with a Star Trek-style island unit. Curvy wall-mounted cupboards have a spacey silver finish and Luceplan light fittings hang over the work surfaces like little UFOs. Beyond the kitchen is the dining area, complete with bespoke oak table (on castors for easy removal during football matches), and the "den". Here squidgy orange sofas were made specially for the house, and Lee's media centre, complete with television and hi-fi, is housed in metallic lime-coloured units also designed by the architect.

A sculptural metal staircase, with a balustrade of wire mesh, separates the den from a more intimate sitting space. Like the dining room, this opens onto a small courtyard where a lean-to was demolished to make way for a garden. Hemmed in by neighbouring buildings, this space, with its white painted walls and water trickling over an abstract sculpture, offers a haven of tranquillity away from the urban bustle beyond.

Upstairs the character of the house shifts again. The open-plan coolness of downstairs is replaced by warmer, stripped red-brick walls in rooms that are open, barn-like, to well-preserved timber roof trusses. A room for the children features the scars of an arched opening on the brick wall and a door leading out onto a high-tech terrace. This steel-framed construction bridges the courtyard, but allows light to filter through its etched-glass floor. Looking out, it is possible to see how seamlessly the house is patched into the dense urban fabric.

Beyond a family bathroom and second bedroom is a further landing with a toughened glass floor and stairs down to the hall. This novel arrangement of having two staircases (a requirement to provide means of escape from fire) allows the children the fun of running complete circuits of the house without having to back-track.

Hidden away in the basement is the house's most spectacular and resourceful space. Here the original cellar, complete with Victorian brick vaults, has been transformed into a shrine to cleansing. A sauna has been squeezed in at the back and a limestone basin and floor added. But most appealing of all is a tub tucked in under the pavement where it is possible to lie and glimpse up at the night sky through glass blocks in the street.

All this is terribly impressive, terribly now. But as a product of the punk generation, doesn't Lee feel uncomfortably bourgeois in his new home? Emphatically not. Firstly, it has that intensely urban quality of an industrial building adapted for living. And secondly, he says, "because it feels a bit like staying on and squatting at the end of a job."

! Marcus Field is deputy editor of 'Blueprint' magazine