As Alan Cherry, chairman of the big housebuilder Countryside Properties and a keen exponent of the new thinking, puts it: "The most important issue is to maximize the use of urban land. Higher numbers are appropriate there." Out on the urban fringes, Countryside and other developers are also upping the densities. For Cherry, though, it is not just about lots of homes per hectare: it is also about mixing up the housing types.
"For 40 years we've been going down the road of segregation - building rows of 4-bed houses with gardens, and ignoring smaller homes for smaller households. What we are doing now is not only mixing the types of housing, but seamlessly mixing the tenures as well."
That means people on subsidized rents living cheek-by jowl with people who are heavily mortgaged, and not noticing: Cherry offers his high-density Greenwich Millennium Village as proof that this can be done. The "seamless mix" approach is also championed by Urban Splash.
The chasm between conventional family homes and apartment living is something that appalls our most famous architect, Lord Foster. Foster may be 69 but he has a young family and lives with them on the eighth floor of the apartment block in Battersea that also contains his vast office. OK, so this is one immense penthouse, no poky flat. There is running-around space. But as he points out, the green acres of Battersea Park are right next door anyway. What's the problem? It's just a matter of balancing the big buildings with the green space. And, he adds as an aside, all the parts of London that are thought to be most desirable - Belgravia, Mayfair, parts of Chelsea - happen to be very high density anyway. True - and so are the bits of central Paris that all the tourists gawp at. Big blocks of apartments above shops and cafes, tended by concierges. It's a system that works.
In the end, you have to consider the alternative. What happens, if the high-density message falls on deaf ears and we continue along the suburban-sprawl route? Foster has a stark warning. "The end result is that, in a very few generations, you will be saying to your kids - we're going to the museum for the weekend. What's the museum, they'll ask? And you'll say - it's the museum of the countryside. You'll say, once upon a time there used to be a lot of this, and it wasn't a museum."
There is a vocal minority in today's planning and economic debate that says that because British farming is on its last legs, and because the housing market is being kept artificially overpriced by shortage of supply to meet the demand, therefore it is only logical to build homes all over the unprofitable fields. Others, such as the Council for the Protection of Rural England, take issue with this and dispute the need to build so many houses anyway. There is also the ecological argument - homes scattered in the countryside generate far more car journeys and pollution than homes grouped more densely in towns and cities, close to good public transport. And even if the countryside is needed less than it used to be for producing food, it still collects our increasingly scarce water and is rapidly being re-forested, to help reduce global warming, improve air quality, and to provide leisure activities. Foster is right. In a small country, if you build all over the countryside, where do you go to get away from the buildings?
