A city will struggle if it can no longer house the people who teach, clean, nurse, cook, police, drive and entertain. In an extract from his new book Slow Burn City, the Observer architecture critic Rowan Moore declares his manifesto – that if London is to grow to 10 million, it desperately needs an intervention.

Cities change. They renew through consuming themselves. Districts are remade and repurposed, populations churn, buildings are adapted or demolished and rebuilt. A city’s fabric is made out of the raw material supplied by the past and becomes the raw material for the future. This includes its cultural fabric – traditions of art, music or cuisine grow up which will be exploited and reinterpreted. Its places are formed, inhabited, acquire value, are appropriated, decline, are recreated.

London has a particular ability to change in this way: areas that can move from one social group to another and between ethnicities, or from industrial to artistic. The common land of a heath might have agricultural purposes, be exploited for quarrying and housebuilding, be rescued for a wider populace, be inhabited by visionaries, radicals, kite flyers, clerks, cruisers, families.

In the first decade and a half of the 21st century, London started consuming itself with accelerating voracity. Change tended in one direction, towards the conversion of all qualities into investment value, especially that of residential property. Such change tends towards sterilisation and irreversibility, without a crash or an external catastrophe such as a war. It threatened qualities that might have been thought fundamental to the city: its availability, generosity, fluidity and social diversity. It looked as if London could consume itself at a rate that might liquefy into profit its vital organs of work and society. Most obviously its desirable areas, its quite nice areas and even those that were just about tolerable were being priced out of range of most of its citizens. More subtle were the ways in which its freedoms and pleasures, even as they grew in sophistication and abundance, were priced and scripted.

The ideal is that cities burn slowly. Their social ecologies and physical forms should renew through change, not be devastated by it. A community and a place cannot be bound together forever, but neither should city-dwellers be threatened with uprooting every few years. Being an ideal, such a city is something never perfectly attained – no one can regulate the temperature of a city as if it were a gas ring on a cooker. London, with its adaptability, its variegation and its areas of slackness and redundancy, has long been an outstanding example of a slow-burning city, but its phases of growth and crisis have also had their drastic aspect.

Put simply, the pattern has been one where private interests have been given freedom to create, to exploit and to grow up to and beyond the point of disaster – fire, disease, overcrowding, sprawl, pollution. There is then major public intervention, in its own way unprecedented, such as the London Building Acts, the sewerage installed by Joseph Bazalgette, council housing, the green belt, the Clean Air Acts, the protection of heritage through conservation areas and listed buildings. These interventions are not only technical, but also political, social and cultural. To make the sewers, for example, required the invention of a new form of city government.

After 35 years in which private interests have again led the growth of the city, it is time for another adjustment. There is already something wrong with a place that expels its poor and puts decent homes beyond the reach of many of its citizens. Even if the problem is seen only in functional and not human terms, a city will struggle to succeed if it can no longer house the people who teach, clean, nurse, treat, make, repair, build, plan, design, create, cook, serve, police, drive and entertain. If the city is to grow to 10 million, the current responses will be – as they already are – inadequate. In their failures, they are also causing damage to the physical environment of the city, wasting its opportunities and endangering its richness.

It might seem strange to speak of slowness when London is dynamic and its challenges urgent and when past forms of intervention – the sewers, council housing – have been dramatic. The actions needed now are not modest. But, paradoxically, large-scale intervention is needed, as dykes and sea-walls might protect agriculture, to allow a city’s human ecologies to flourish.

We might even hope that London could do better than Bazalgette, a century and a half on, and, while working at a scale equal to its largest-ever size, encourage growth through local and individual initiatives. Take, for example, self-build housing, a concept promoted by governments right-wing and left, but, despite the inspiring work of Walter Segal at Walter’s Way in Lewisham, almost never achieved. This is because would-be self-builders can’t compete with the land-buying powers of property companies. It would require public authorities to designate land on which individuals could build their own homes.

In his 1959 book Experiencing Architecture, the London-loving Danish architect Steen Eiler Rasmussen wrote that “the Londoner calls his sidewalk the ‘pavement’ and a more cultivated example of paving can hardly be found”. The accompanying photographs unfavourably compare a Danish example with one in Bloomsbury, the former a harsh combination of concrete, asphalt and granite, the latter a harmonious pattern of York stone, “pleasing to the eye and comfortable under foot” and neatly punctuated by the cast-iron covers of coalholes and inspection chambers.

Copenhagen has so long ago overtaken London in the field of civic design that it is outlandish to think that things might once have been the other way round. The modern London pavement is more likely to be a conflict zone of taking-up and putting-down, whether by utility companies, data providers or local authorities, of pink paviours garbled with grey, black gobs of asphalt, cracks, spots of gum and phlegm, mismatched bollards and sometimes the residue of hopeful art projects, where the void in the res publica was to be filled by a morsel of underfunded wit.

One response would be to call for the restoration of the pre-war municipal virtues that made the pavements that Rasmussen admired. This would be a good start. If local officials and politicians could be persuaded of the benefits of doing things simply and well, that the exercise of a little intelligence early in the planning of a place can save expensive stupidity later on and that basic dignity should be the minimum for shared spaces, it would be a leap forward. It might seem quixotic to think of such a thing at a time when the attitude of national to local government is one of pummelling, binding and starving. But such things can change.

At the same time London needs more than a Scandinavian perception of its 1930s order, no matter how enlightened. It should be remembered that the municipal is not always virtuous and that at least some of the damage done to the city has been in the name of planning. Arguments in favour of spontaneity and against overdetermination by officials need to be heard.

Here, one is back to the swing between plan and non-plan that was the underlying pattern of postwar development. Both have proved emancipating and beneficial and both have been prone to abuse and appropriation by special interests. Plan kept at bay the kind of housing crisis that London now faces, built outstanding council housing at Churchill Gardens and Golden Lane, created open spaces and new towns, built roads which, however clumsy, serve a purpose, and enabled places of education with the qualities of the best post-war schools. It also created the waste and rigidity. The spirit of non-plan is in both the squatter-led flowering of Bonnington Square and in Canary Wharf, adventure playgrounds and the Thames skyline. At best it enables both bottom-up initiative and entrepreneurial wealth creation. At worst it allows the seizure of common assets for profit.

The truth is that London needs all of everything: plan and non-plan; popular action, public intervention and commercial investment. They have their own forms, their own benefits and disbenefits, their own extremes. The ideal for London is not the smoothing-over of these differences in the name of an overall homogeneous order, but their vigorous co-existence. Better the self-declaration of a Canary Wharf than the stealth-wealth of other parts, as long as the spaces for those outside the financial services industry also have their strength and dignity, and due attention is paid to the connections between such zones. Let there be Versace towers, if they rise out of public spaces of equal ambition and conceivably better design.

London is made of everything already. The transport system is a creation of both piratical speculation and orderly public management. The high property values of Hampstead rest on the public protection of the Heath, the actions of private citizens’ campaigns that brought it about, the sculpting of its land by commercial exploitations, its protection in Tudor times for the purposes of royal hunting rights. Canary Wharf owes its success not only to the entrepreneurship of its developers, but also to the 1799 Act of Parliament that created the West India Docks, to the tax and rent breaks of the London Dockland Development Corporation and to the construction with (mostly) public funding of the Jubilee Line extension.

Whatever is done in London has to take into account existing interests, with whom some sort of pact is usually required. The multiple exceptions made for the City of London, which was there before everything else, bear witness. Victorian philanthropy towards the poor was partly motivated by fear, preferred some of the working classes to others and was often more about getting slum-dwellers out of sight than about helping them. Change of policy requires struggle, as can be seen in the decades-long effort to preserve the commons, whose motivation was not wholly altruistic but included the desire of proto-nimbies to protect the spaces near their homes. Political structures have to be respected or at least understood, in particular the ways in which the 32 boroughs, plus the City of London, have more effect on the shaping of the capital than the mayor or anyone else.

But unprecedented change can happen if enough people push for it, like those protesters who demolished the railings that once ringed Hyde Park. The present city owes its parks, its freedoms, its health, its efficiencies and its desirability to such change in the past.

A manifesto for London

The ideal of London is that it is available and open. It gives opportunities and freedoms. Its common assets can be shared by all. It is competitive but generous. All identities are possible, but not mutually exclusive.

The city has two main needs:

•  new and accessible homes

• enhancement of the qualities that make a city worth inhabiting

MAKE HOMES

It is clear that, in the early 21st century, the most critical issues facing the city are to do with housing. It is a crisis of price and supply that:

• creates a class of people who can no longer afford to live in the city

• creates a class of people who continue to live in the city at the cost of accepting exceptionally poor living spaces

• generates favelas: beds-in-sheds, grossly overcrowded flats.

It has other damaging effects. It:

• distorts choices in personal lives, in relationships, in decisions whether and when to have children

• inhibits the free movement of people, and of labour

• exiles people vital to the functioning of the city.

It has been created by:

• national government policy that has encouraged house price inflation for a generation

• restricted supply and high demand

• the inability of the private sector, at any time since the 1930s, to meet need by itself.

It will only get worse as the population increases. Therefore:

• more space must be made available for new neighbourhoods

• government (national, London-wide, local) must build when the private sector won’t; governments should own land and guide building on it in the public interest

• national government must stop pushing up the price of homes.

Ways to make more space include:

• making existing streets denser: two storeys can become three, four can become six

• intensification of outer suburbs, especially in their centres, without destroying their essential characters

• building on formerly industrial land, but not at the expense of vital businesses

• building the transport, schools and other essentials for making new neighbourhoods work

• towers, if they fulfil their promise of being well designed and in the right place

• building (with care) on the green belt.

The green belt, invented for the benefit of Londoners, is now causing the city to suffer. Building there could not only create more places to live, but also give more people access to nature. The traditions of making town houses with gardens, admired by Rasmussen, could be revived. A dull field, given to the city, can make a richer contribution to human life than when left alone.

These options do not exclude each other. All are needed. All require planning.

People who oppose building near their homes often have good reason to do so. They should therefore be able to share in the benefits that come from new development.

MAKE NEW PLACES. PROTECT THE EXISTING

• Reverse the degradation and erosion of the city’s shared spaces and encourage new ones to match its expansion. As the best parts of London are removed from the reach of most of its citizens, it is essential to make good new places to replace them.

• Stop further devastation caused by tall buildings to the Thames and other parts of London, both long distance and close up. Enforce the principle that the more conspicuous a building is, the more care should be taken in its design.

• Planning has to support the qualities that make shared spaces succeed, including the relationships of buildings to each other and the qualities of the surfaces.

• A city is not a gigantic housing estate. Support the vital places that are not homes: for working, sociability, knowledge, health, imagination. These include high streets, gardens, factories, clubs, markets.

• The city should include slack space – places where people can do their own thing, create urban gardens, allotments and playgrounds. Again, an acre of such space is worth more than an average acre of green belt.

• Value the already-there when making the new.

PLAN

• Simplify planning rules; reduce the roles of opinion and obscurity.

• Employ more planners; value and pay them better. The amounts spent on guiding development well are tiny compared with the billions spent on construction. Investment in intelligence early on saves waste later.

• Require that definitions of sustainability take embodied energy into account.

• Conceive areas of new development as places not diagrams. Consider the spaces made in three dimensions. Recognise the qualities that make a place distinctive and successful. (Clue: it may not be topiary.)

• End abuse of terms. Something described as “public space” should be fully public. Ignore words of puff such as “iconic” and “world class”.

• Planning is not just the mitigation of damaging proposals, but the active encouragement of areas and buildings that enhance the city.

DON’T PLAN

• Planning does not mean that planners make all decisions themselves, but create conditions in which local and individual initiatives can flourish.

• Let there be places for large and small enterprises. Let there be zones of hyperdensity, if the market wants it, and self-build housing, Canary Wharfs and Walters Ways. Make space for experiment and transience.

• Give London the freedom to make the most of its resources and energies. Give its citizens the freedom to live well there and make the most of the city.

There is a view that London has never been more marvellous than now, in its energy and wealth, in its concentration of creativity and concentration, in its pleasures and freedoms. Suggestions that there might also be problems are met with accusations of party-pooping, and the assurance that the bounties of the market will benefit all. Towers and iceberg houses, goes the argument, should be celebrated as signs of success.

And, indeed, the city is fascinating and exciting, but the bigger point is this: if London is so brilliant, why not apply that brilliance more widely, such that it can boast to the world of its public housing and city planning, the unrivalled intelligence and beauty with which its new towers are directed, its city-transforming ways of draining rainwater, its encouragement of thousands of projects to build homes, grow gardens and improve streets? Why not apply the ingenuity that currently goes into massaging the planning system, such that multi-level basements might be permitted beneath historic houses, to addressing the city’s larger needs. Which would in the end benefit everyone, including those overseas investors that London’s politicians have been so anxious to court.

For whatever thrill might be had from a glass swimming pool would be more thrilling if part of a wider environment that was itself exceptional. London has an ability to reinvent itself decade by decade: why not make its next invention be the rediscovery of its generosity?

This is an edited extract from Slow Burn City by Rowan Moore, published today by Picador, £20. Click here to buy it for £16.

This feature originally appeared in The Guardian.

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