When will we admit that London is full up?

By 1972, the British population had soared to 55.5 million. Now the figure is 60 million - and the Office for National Statistics has just forecast that by 2031 it will be more than 70 million. Some 70 per cent of this rise will be a direct result of immigration - and much of the rest due to births among secondgeneration immigrants.

These official figures have come, supposedly, as a shock to the Government. Even three years ago, it was thought overall annual immigration would be running at just 145,000 a year. Now it has been admitted that there are 215,000 long-term migrants to London alone each year.

The difference will throw out all plans for housing, education, healthcare and transport. Yesterday a health minister forecast that within 10 years, "we will be back to where we were with people waiting on trolleys in A&E departments, unless things change".

There are two debates here. One, about whether or not British society can retain its cohesion with such large communities arriving from different cultures, is difficult, susceptible to nationalist, if not actually racist, hijacking.

But the other, the debate about sheer numbers, should be straightforward. London and the South-East is already one of the most densely populated regions of not just Europe but the world. There are too many people here for the space. We all live with extraordinary pressures as a result. The streets are packed, the transport system bursting. And what we have done about it is choose not even to discuss it, let alone try to influence Government policy. We just flee, when we can, to France, to Spain, to Australia.

Back in 1961, JG Ballard wrote a terrific story called Billennium, about a man reduced to living in a cubicle on a staircase in an old rooming house, now hosting more than 100 people. In this grim future, the government allows a maximum living space per person of four square metres. The streets are so full that even pedestrians sometimes become gridlocked for hours.

Population statistics are classified, for fear of mass attacks of claustrophobia. The countryside no longer exists.

All that Ballard seems to have got wrong is that he imagined this crush being regulated by the state, rather than by the market. Otherwise, that's the way we're heading.