Until 18 months ago, Dorothy Berwin and Seth Stein lived in his little-larger-than-a-doormat bachelor flat. Very high-tech, it had aluminium floors, aircraft chairs from a jumbo jet and the most minimal minimalism. Dorothy kept most of her clothes in a mobile wardrobe unit-her car. ‘It was like being on a constant camping holiday.’

Now Dorothy and Seth have made a few changes. They have got married. They have moved into what was a former Notting Hill Gate nurses’ hostel-and they have developed agoraphobia. Their old flat would fit into their current kitchen, and you could land a microlight in the new sitting-room. ‘We used to lie in bed, stare at the ceiling and wonder how long it would take to walk there,’ says Dorothy, 30, grilled-vegetable enthusiast, red Comme des Garcons skirt lady and head of business affairs for Zenith Productions, a leading independent film and TV production company. Seth, 31, in Ralph Lauren shirt and Levis, laughs.

She’s impish and clever; and he-with a dry wit and gentle disposition-is New York gone Barcelona: the former by birth, the latter in looks. When they first saw the conversion, Dorothy’s mother-a lady of some taste-said: ‘Isn’t it wonderful? You can move straight in.’ And then Seth ripped it apart and demolished it.

Built in 1850, the building-of which they bought the ground floor-had previously been full of nurses’ bedsits in decline. Their current 50-foot sitting-room was four bedsits. This hostel had been connected by a passageway to the block behind, a hospital.

But the flat on which they exchanged was a luxurious new development. ‘It had serious gold handles and lots of twiddly bits everywhere,’ explains Dorothy. For ‘twiddly bits’ read chair rails, decorative tiles, frilly knicker Osborne and Little curtains and trellis-work motif on the best quality handmade Colefax and Fowler carpet.

And so they set about tearing down the brand new curtains, stripping the flat, ripping up carpets untouched by human foot, bartering a marble fireplace for a generous Thirties sink from the Dorchester, getting rid of all ornamentation and knocking down walls. All achieved with some pocket money and what they dub low-budget expensive taste.

The thing you need to know about Seth is that he’s a talented architect who worked for Richard Rogers and then Norman Foster, whom he left 15 months ago to set up on his own-in other words a baby of the high-tech generation who has discarded his aluminium nappies for modern clothes sewn with much care and attention to detail.

His work-relished from Islington to Italy-is about modernism that is not alienating, stark or cold.

Take their sitting-room. You burst into it through a Tutankhamen passage. Asymmetrical, with tapering walls of natural pigmented plaster, it gives a feeling of length and perspective.

Inside, there are soft white walls, motorways of white silk curtains, a chandelier of white Christmas fairy lights with clothes hanger wire, a fire with a concrete hearth set with Seth’s collection of pebbles picked up on beaches, a Sarah Charlesworth diptych-half of which is all black-called Fear of Nothing, and an acre of vegetarian carpet (Seth’s name for seagrass). ‘When it’s damp, you can throw alfalfa seeds on it and they sprout. Come the siege, we’ll be able to live on it for a month.’

Then there’s the furniture-or rather, there isn’t. ‘The typical situation is to go either to Conran or IKEA.’ Seen It Before, in other words. The little but great furniture there is was designed by Seth, apart from the Bonnetti and Garouse-they did the Christian Lacroix showroom in Paris-rope-coloured curvy-backed sofa and an Eileen Gray chair. There’s a dining table made of salvaged yet still distressed Victorian floorboards on a modern steel frame. A fire-engine-red table, a graphic solid square which tapers to a rectangular base off-centre, irregular and appearing to float. And not much more.

It was here that they recently held a party for 200 friends: a flat-warming-cum-engagement do, with Sixties moving blob oil projections on the walls, dry ice and funky music-all because Seth always wanted to be on Top of the Pops.

Next door is the study, nocturnal and introspective with its big white door with a single steel handle, grey varnished plaster and high-tech bookshelves that aren’t bookshelves-they’re floor decking for warehouses-clutter and Fornasetti classical motif Fifties-shaped chairs. The kitchen-with natural materials, handmade terracotta tiles, timber cabinets, stainless steel with linen finish, fig trees and Dorothy’s mother’s 30-year-old cooker-is not just modern, it’s ergonomic. The inspiration for the flat came from a Manhattan loft space. ‘As London gets more like New York City in terms of pace and grottiness,’ says Seth, ‘you need your home to be more of a simple haven away from the stress. We fantasised about having a large, white, simple space.’ Simplicity. Ah, simplicity.

BARBARA Chandler’s Supersaver is a Fagor white or brown built-under electric oven with hob controls, plus gas hob and electric hood for £375 (usual price £500). From Buyers and Sellers, 120-122 Ladbroke Grove, W10 (071 229 1947/8468), while stocks last. Credit card orders accepted. Please show or refer to this edition of the Evening Standard to qualify.