Situated on the first floor of a grand 1850s terrace, No 53a England's Lane, Belsize Park, benefits from the natural light flowing through the tall sash windows.

These, along with characteristic high ceilings, compliment the contemporary furniture and fittings, which include a functional galley kitchen with practical open shelving. A new extension comprises a generous master bedroom en-suite and a guest bathroom.

The impressive refurbishment is all down to the owner, Irish architect John Munro, and the secret behind this clever take on open-plan, dualuse living space is the custommade, bi-folding doors and a 5x3m moving wall. Which all look a lot more stylish than they perhaps sound.

These flexibile additions allow for the opening-up of the main living space, while also offering the creation of a second, guest bedroom, when needed.

The rest of the time, this space functions as a bright home office.

John, who trained at the DIT in Bolton Street, Dublin, and subsequently ran his own practice in Warsaw for five years as well as working with high-profile architects such as Norman Foster, explains the philosophy behind the radical redesign of the property, while recallling with a shudder what the place was like when he initially bought it: "Pink carpet throughout and 11 power sockets.

"The overall problem was that, like so many period houses in big cities, it had been subdivided by developers over the years, with profit, as opposed to aesthetics, the driving force.

"It suffered from that phenomenon of landlords remodelling properties for residential use on the 'one-window-equalsone-room theory', " says John.

"Irrespective of generous ceiling heights, light and proportion, the rule chops the original design into the minimum footprint for your typical two- or three-bed flat."

The property had orignally been configured as a two-bed, one bathroom flat with a long narrow corridor and a 'landlocked' bathroom separating the main living spaces. Living patterns and expectations have changed with people demanding a more pleasing, yet functional home, says John, and many people now take their work home.

"The workstation is an almost ubiquitous piece of furniture these days, and the second bedroom has become an office-cum-occasional guest bedroom."

Where a dual-windowed room has been crudely subdivided, it can mean that a large proportion of potential living space is hardly enjoyed.

The second bedroom at number 53a was effectively redundant most of the time as a result, says John, and knowing also that the flat roof (over the gallery below) regularly leaked . . . he decided that a complete overhaul was required.

By extending out over the flat roof of the gallery, additional space was created, coming together as a master bedroom suite with bath and power shower ensuite, and also a roof-lit wet room cum guest cloakroom.

The result is a bright inviting home with the sort of flexibility to suit any number of buyers . . . and one that shows London still swings.

Price: £600,000 ( 866,711) Agent: John D Wood, 0044 - 207 586 9060