Property: Thoroughly modern Moro

On a dull, grey day in south-east London the open-plan living- room is filled with light. Through a glass wall, the grass and trees seem an extension of the house itself, natural, simple and uncluttered. It was built as a family home in the late Fifties and described by its creator as "just an ordinary, modest house". Nothing, though, could be less ordinary.

For this house is Grade II-listed and the most personal legacy of the renowned architect Peter Moro, who died last year. His public work includes the Royal Festival Hall, the Nottingham Playhouse and the Theatre Royal, Plymouth; his own house, in Blackheath Park, is true to the Modern movement in its economical and functional design.

"He had a hatred of neo-classicism," says Alice Moro, his daughter, who grew up in the house. "It made his blood boil. We used to live in a Georgian house but he always said that since he had the ability and financial means to build his own house, he wanted to be true to himself. He loved it here and never had any regrets."

Few changes have been made to the house over the years. The layout in the living room, some shelving and the addition of built-in cupboards were altered to meet the family needs, but the detail and the concept of living are unchanged. "It is a wonderful house for parties and my parents did a lot of entertaining," says Alice. "It was novel then to be able to stand in the kitchen and talk to your guests. I suppose I took everything for granted but my friends who were used to antimacassars on chairs thought it was great."

But how difficult was it not to break the design rules of a minimalist father? "Fortunately my mother didn't want to put up swags and tails at the windows so it wasn't a problem. I could do what I wanted with my bedroom - I painted it orange. The sleeping area was intended to give a very different feel, private and shut away. I did rather long for a few Staffordshire dogs about the place but the only ornaments I can recall seeing were lovely old goblets, a big glass sphere and a skeleton clock."

Moro's is only one of 32 private houses from the Fifties and Sixties to be listed. Often the facade of period buildings is all that is left to be preserved, giving the owner virtually a free hand within the four walls. But the buyers of the Blackheath house - a neighbour of the largest batch of Eric Lyons-designed Span houses, also listed - will find themselves having to embrace it lock, stock and barrel. The colour scheme, pine ceilings, door furniture, switches and black floor tiles are as vital to the spirit of the house as the free-standing fireplace and central staircase.

At English Heritage, Elain Harwood, listing inspector and historian, says there is a growing appreciation of such houses. "They are one-offs, and even if someone doesn't know the architect, buyers are likely to walk in, say "wow", and then go and do some research. But they do have to appreciate they are looking at a design classic and be aware of the limitations. Having said that, we don't expect a house to be frozen in time and its listing is really a matter of putting down a marker so that any changes are done sensitively and with some discussion."

In Hampstead, north London, Lisianne Newman of Goldschmidt & Howland finds opinions about listed buildings generally divide between those who regard a house with a name or history attached to it as an asset, and others who see it as a hindrance. Hampstead's terrace of three Erno Goldfinger houses, with their large windows, spacious open-plan living and curved staircases, are a case in point. The last time one was sold - a couple of years ago - it went for just under a million pounds. Those who loved it would find it hard to understand why even in such a prestigious area others would never consider it.

But the criteria of those who decide what features of a building should be preserved have also swung like a pendulum. Many people in the business of converting and restoring old buildings question some of the restrictions imposed on them. Do the old floorboards really have to be retained and the floor stay uneven? Should the entrance porch be put back in the style of its immediate post-war neighbours or as it was orginally?

A couple who have just bought a Georgian house in a conservation area of north London were told how the vendors had to get permission to put up a small wooden gazebo on the extension. It was only 15 years ago that the extension was built and at the same time a tiny sash window on the top floor was replaced with a far larger one. The house is now light and far more spacious than current regulations would be likely to permit. While its new owners recognise that the changes were not entirely in keeping, they are doubtful whether they would have bought the house in its original state.

Such thoughts have occasionally passed through Alice Moro's mind as well. But now that she is looking at her father's house through fresh and more critical eyes she finds she has come to really appreciate it. "I grew up here and accepted it without question. Now for the first time I have fallen in love with it."

The guide price for Peter Moro's house is pounds 585,000 (contact 0171-403 3166). Hamptons International, 0171-738 7622; Goldschmidt & Howland, 0171- 435 4404