The belle of Belsize Park

So, the £4.5m price tag is a tad beyond most pockets, but where's the harm in dreaming, writes Cheryl Markosky

It can do no harm every once in a while to fantasise about the kind of house you would buy if you won the lottery. You know the sort of place. It has all those practical features like under floor heating, air conditioning and utility room with an enormous American washing machine, drier and a second dishwasher - after all, you need some back up if the first one tragically breaks down mid-dinner party. Naturally, it is aesthetically pleasing - but in a terrifically subtle kind of way.

It can do no harm every once in a while to fantasise about the kind of house you would buy if you won the lottery. You know the sort of place. It has all those practical features like under floor heating, air conditioning and utility room with an enormous American washing machine, drier and a second dishwasher - after all, you need some back up if the first one tragically breaks down mid-dinner party. Naturally, it is aesthetically pleasing - but in a terrifically subtle kind of way.

Although it might feel you are pressing your nose against the sweet shop window if you can't stump up the £4.5m price tag, you could do worse than dream about owning 1 Belsize Square, the latest creation from niche developer Gary Sugarman at BTO Ltd, and designer Rachel Harding of Rachel Family Ltd.

Semi-detached in north London's Belsize Park, the 5,000sq ft period house was a motley collection of bed-sits until BTO bought them two years ago. "An agent came to see a house we'd just finished in Primrose Hill and said if we could do a job like this we might like to see this wreck in Belsize Park," Sugarman says. "We saw the house on Tuesday at 5pm and bought it on the Friday."

We should be grateful for Sugarman's impulse purchase that has taken 18 months to convert. Harding says she is "getting down to the fun part" now, kitting out and applying finishing touches to the interiors. Luckily, the house is not listed and only one fireplace - now situated in the first floor master bedroom suite - was worth preserving. "It belies the grandeur that was here before," she says. She has reinterpreted the old cornicing cut into shadow gaps in the ceilings and installed oversized skirting boards and doors, tricks emphasising further the opulence of the past.

Harding, a 35-year-old law graduate and former estate agent, is a self-taught designer who combines no-nonsense practicality - the gardener can access the utility room through a side door and the garden without going through the house - with aesthetic ideas that push the boundaries. "I have not trained formally, so I think on a bigger scale and question things. I think architects spend too much time looking at boxes on a screen. A place I worked on planned by an architect didn't work - I had to re-design it. It is about flow and space and you need to spend time on site to work that out," she says.

The joy of Belsize Square is that, not only is it filled with all the goodies you desire, and some you didn't even know you had to have until you see them, but they are within a structure that relates to how people really live.

There is a "proper" entrance hall, separated from the living room by double walnut doors set into a curved textured purple wall in Marmarino plaster. Soft, grey, lead-coloured walls from the architectural collection of the Paint Library run throughout the house, contrasting with dark fumed oak flooring and stairs with a paler English oak-clad balustrade.

The living/entertaining areas run over the bottom two floors, while the master bedroom suite covers the entire third floor, with further bedrooms and bathrooms above and a terrific top fifth storey office/media room/studio with private balcony. "Kids who come up here immediately commandeer the space," Harding says. She has installed plumbing in case anyone wants to add a shower or kitchenette.

"Pretty much everything is bespoke," explains Harding. "I had the marble grey basin in the downstairs cloakroom specially made, along with the Italian Porro oak veneer units in the first-floor dressing room and the limestone basins in the his-her bathrooms." Travertine marble splashbacks, basins, a shower and even shower trays book-marked to match show how much attention to detail has gone into the scheme. With most developers in the area playing it safe and sticking to traditional looks, Harding has come up with a contemporary style that manages to be friendly - and even homey within such large spaces. She believes lighting is important and has installed a Lutron system with 54 circuits to programme different moods for different times of the day. Surround sound music is fitted throughout, without any brash over the top speakers.

"The Minotti kitchen is minimalist so there is an area where you can put your stuff and close off the doors," points out Harding. "In contrast, sandstone from Italy makes the worktop a little bit organic. I like mixing the soft with the hard." You can relax on a sofa in a family area off the kitchen, which leads out to a three-tiered garden: a limestone terrace, followed by a grassed area and a softer Iroco decked space surrounded by silver birches. There is planning permission to erect "a glass box like a Japanese tea house for mediation" for an extra £25,000 - a snip if you have already forked out £4.5m.

Already there has been interest in the house from prominent figures such as the director Anthony Minghella, the actress Gwyneth Paltrow and the songwriter Guy Chambers. Selling agent Grant Alexson, from Knight Frank, says: "This fantastic design with lots of glass is likely to appeal to a modern buyer - someone in the media or a lawyer, perhaps - who hasn't got the time to do up a place."

Locals have been knocking on the door, according to Harding, asking for tours round the house. "There has only been one anonymous ranting letter written in several different colours of ink with the PS making up the last three of four pages. I want to put up a board asking Anonymous to come in for tea and take a look around. I bet they would like the house once they saw it."

Harding confesses it will feel odd parting with the project that has filled the past two years of her life. "It is like looking after a baby and then not feeling it is quite ready to go to school and have outside influences."

Belsize Square is available through Knight Frank (020-7431 8686), Aston Chase (020-7724 4724) and Arlington Residential (020-7722 3322)