Does London really need more housing restrictions?

It was the time of high prices and small flats, of balconies so shrivelled as to be useless, of gimcrack design, of midget bedrooms and sunless north-facing homes.

Anyone wishing to swing cats could forget it. Thanks to the great buy-to-let frenzy, buyers lost sight of all notion that units of accommodation could be homes, and treated them instead as abstract units of currency.

Now the tide has ebbed, it has left behind an ugly scum of unloved and unsold flats.

But here comes Boris Johnson riding to the rescue, railing against "Hobbit homes" and flapping his arms and wielding his capacious form in warning against the perils of the compact.

He wants to bring in rules to prevent titchiness, and no one could argue against that.

But he has prompted a chorus of developers, large and small, to warn that his rules will make a home even rarer and more expensive than it is already.

They say you, or your children, will find it even harder to get one.

Today, the Mayor unveils his draft London Housing Design Guide. This describes the Borissian dream home, with minimum sizes for different types of dwelling but also rules about ceiling heights, balcony widths, sunlight, the preservation of biodiversity and water conservation.

It insists on "lifetime homes", which means making sure that if you become disabled - and most of us at some time will - there is enough space for the wheelchairs and other gubbins you will need. You would not, therefore, have to move out.

The Guide describes little paradises of well-dimensioned, environmentally-responsible domestic bliss.

It draws on the Parker Morris standards of minimum sizes, which were invented by a moustachioed wonk in the Sixties, and applied until another blonde-maned Tory populist, Michael Heseltine, abolished them during Mrs Thatcher's first term.

It then increases these standards with lordly largesse by 10 per cent. Boris Johnson, freewheeling columnist, chatshow star and champion of individual liberty, has become almost Swedish in his love of rules.

These standards are, he hopes, to be applied to all housing developments where there is public investment, which means not only affordable homes built by housing associations, and all housing built on London Development Agency land, but also any private development that includes some subsidised affordable housing, as most do.

The intention is to enforce these new rules one day on all new homes, through the planning system.

The Mayor finds himself applauded by people who may not be his natural allies - Left-of-centre architects. Sunand Prasad, President of the Royal Institute of British Architects, says it is "high time that there were good space standards"; they will "leave a better legacy of more flexible and adaptable homes".

He says that the impact on cost will be "very small", as most of the price of a home is in the land value rather than the construction cost, which would go up by "less than five per cent".

The increased cost of building would be "laughably small" compared with the bulimic fluctuations in house prices caused by booming and busting cycles.

Most steps to make homes better, such as regulations on fire, or insulation, or health and safety, are opposed by housebuilders for increasing cost but in the end the market adjusts, argues Prasad, and land values drop to take account of the added cost of building.

Others are less convinced. Developer Crispin Kelly says the principle of standards is "absolutely right" but that the rules might lead to "20 per cent fewer units being built", which will leave thousands of disappointed people unable to buy homes.

He also doesn't want "more ways in which planners can tell us what to do". It is "another load on the industry" which is already asked to subsidise affordable housing, and improved roads and pavements.

The former housing minister Nick Raynsford thinks regulations can "stifle innovation" and generate a box-ticking attitude.

He points out that the huge Ferrier Estate in Kidbrooke, south-east London, was built at a time when the Parker Morris rules were at their height but was still catastrophic in its effects. Rules alone don't make decent homes.

It is also argued that the Guide is another work of bodger Boris, a mayor in love with the sweeping gesture, but bored by the detail needed to make things work.

"It is a proposition without evidence or knowledge," remarks one in the business. "Where is the proof that housebuyers want these standards, or that they will make homes better, or that they will not put homes further beyond reach?"

The fundamental problem is this: the main reason why we, one of the wealthiest countries in the world, built terrible and expensive housing is that the people who build houses, and the people who buy them, treat them as speculations more than as places to live.

This is because, in boom times, lenders will offer mortgages of more than 100 per cent of the value of a home. It is also because the planning system strangulates the supply of land and pushes its price up.

We have become hooked on housing inflation, and boom times will come around again, once enough time has passed for amnesia to descend on the pains of a crash which we are now experiencing so vividly. This is what always happens.

It is beyond the power of Boris and his rules to change these forces, and there is indeed a risk that he is merely adding another layer of meddlesomeness and obstruction to the system.

Yet flats, once built, last for decades and centuries and it is sane that they should have some basic level of quality. It is hugely welcome that a politician is trying to do something about the quality of the places where we live.

So Boris should forge ahead with his rules, while paying due attention to any flashing lights and bleeping sirens on his control panels warning that he is indeed un-housing future generations.

In a perfect world his rules would be combined with other, compensating, measures to reduce interference from planners but we could wait forever for the perfect conjunction of national and mayoral policies that would address every flaw in the way we build homes.

You have to start somewhere. But Boris should also get his friends in the Conservative party, the probable government-in-waiting, to work out ways in which all the pressures that lead to dismal housing - including the financing and planning of homes - can be addressed.

The London Housing Design Guide can be read at www.london.gov.uk.