I don't think his point is very well made, though. First, the issue is not so much planning permission, as in all the externalities that the planning process seeks to capture. In many parts of London at least, the councils and planning offices are falling over themselves to be helpful to developers, but they still have responsibilities to residents they need to be mindful of.

While it is true there are some limitations on building up in central London, for example, vast areas of London is not built up to anywhere near the legal limits. As we see, as there are massive amounts of building projects in Central London aiming to increase density. Over the last ten years, for example, large parts of the Thames have seen buildings of 10+ stories going up next to the river on old industrial sites, with many towers of 20+ stories.

As for the green belt... Croydon, where I live, is out in zone 5, bordering the green belt. It's one of the greenest boroughs in London, and also one of the largest (5th, after Bromley, Hillingdon, Havering and Barnet). Yet it also have large industrial areas, a large business district with substantial space for re-development, and several empty plots cleared for re-development. Space is not the limiting factor for developers here. In fact, there is space on vacant plots immediately adjacent to the main railway station for many thousands of new flats, several of which have planning permission.

We also have massive areas of 1930's terraced houses, on plots of about 100-200 m^2, and total liveable area of about 70-100m^2 over two floors. There's massive room for increasing density there just by building 4-8 story buildings. There, certainly, there's lots of room for streamlining the planning process. But hardly anyone are applying for smaller projects like that.

Typical new developments in Croydon are 20 floors or above, with one 44 floor tower going up, planning applications going in for a combination of a 16 and 31 floor tower next to the station, planning permissions near being granted for a range of buildings from about 10 to 30 floors next to the station, a major mixed project including other towers in the same range have had permission for years. And there are a number of other similar projects.

The thing is, this is not cheap, nor is it fast, and furthermore: It takes a lot of time to fill these buildings in the current economy, which has also slowed various of the building projects that does have permission. Altitude 25 - one of our existing 25 floor buildings, is still not sold out after several years.

There's no reason to go into the green belt when there are such massive amounts of land available to build on that is still under-developed.

More importantly, though: It's easy to fantasise about increasing density, but increased density has massive societal repercussions that someone need to pay for:

- You need more schools. Croydon is already struggling to handle the increase in primary school demands from the new development that is happening. My son goes to a new academy which, when full, will take 750 students. The current classes are full, and all the other nearby schools are near capacity again, though, despite adding classrooms and increasing students per class.

- You need more hospitals. Croydon's biggest hospital is near capacity. Increase density much, and massive investment will need to happen to expand hospital capacity.

- Policing, fire department, higher education, sanitation, etc. etc. - the investments needed costs a lot of money, and much of it needs to happen before significant housing capacity increases unless you want existing residents to go through years of pain while services catch up. Ultimately you may end up paying less per tax payer than before by increasing density, but in the meantime you may be looking at substantial capital investments to prepare.

- Transport. My street is one of the main roads connecting Croydon centre to one of the smaller town centres in the borough, and two of the busier train stations. It is already congested during rush hour, and buses are full. Increase density more, and substantial investments would be needed in improving transport, or you'd cause massive issued for tens of thousands of residents. You won't get more people onto the buses withought buying more buses and adding more drivers. The biggest train station is already being massively overhauled, because it is at capacity and additional highrises nearby will push it way above capacity from additional commuters. It is already one of the busiest stations in England, and a chokepoint for large parts of the train traffic from parts of the South coast to central London. They've set aside space for two extra tracks to terminate, but where would the trains go? The train junctions North of East Croydon are running at capacity most of the day, and large parts of the track is running at near capacity, and the areas next to them are built up almost all the way. The investments required to substantially increase rail capacity will run in the billions - someone needs to pay...

A lot of this is part of the planning process. You can not just massively increase density without addressing these issues, and how these things are going to be paid for.