Visions of an overcrowded Britain can quickly veer into an uncomfortable debate about immigration. But if the latest projections for population growth are right, the implications for planning could be huge.
Longer life expectancy, higher fertility and migration are driving a population boom. Office for National Statistics (ONS) figures published last week (Planning, 26 October, p1) point to a population of 66 million by 2020, 71 million by 2031 and 77 million by 2051.
The projections point to a much faster rise in numbers than previously estimated. The last 2004-based projections predicted a slower growth rate to 67 million by 2031 and 69 million by 2051. Growth in household formation, currently expected to average 223,000 a year up to 2026, is already placing pressure on housing delivery.
For University of Oxford professor of demography David Coleman, the figures confirm his view that population is growing significantly faster than previously thought. Such changes will have a huge impact on life in the UK, he believes. The biggest implications, he adds, are for the south of England, because that is where most people coming into the UK end up living and working.
"If this growth comes fast it will have quite serious consequences for housing, roads, transport and water supply, particularly in the southern half of the country," he argues. "House prices are going to be sustained by it. The government will have to manage growth but it could be at serious cost to the level of amenities and standard of living."
The RTPI emphasises that the figures highlight the need for a national planning framework to manage a growing population. This would help plan infrastructure more comprehensively as well as identify opportunities to redirect growth to underperforming areas outside southern England, it maintains.
But others believe that if the projections are right then something must be done to curb such growth. The Optimum Population Trust (OPT) insists that the UK will be sleepwalking into an environmental disaster if no action is taken.
"The government has already presided over the fastest growth in UK population since the baby boom years of the mid 20th century. If it continues to countenance population increases on this scale, it will be embarking on a vast unplanned experiment with the UK's well-being," says OPT spokeswoman Rosamund McDougall.
For the past five years the charity has been urging the government to adopt a policy aiming to stabilise and then reduce the UK's population to reach a target of 53 million by 2050. "We desperately need to start thinking about a national population policy, spelling out how many people the UK can support environmentally and what we can do to achieve it," says McDougall.
She suggests that this could be achieved by promoting smaller families, reducing unplanned teenage pregnancies and balancing immigration and migration flows. "Until recently we have met a barrier in government. Population has been looked at with a predict and provide approach. One hopes that the penny is dropping at last," she says.
Government statisticians insist that it is down to ministers to work through the implications of the projections and decide what strategies need to be in place to cope with a potential surge in numbers. It looks as though a rethink will be needed on housing, transport, health and education services, posing a further challenge for spatial planning.
Coleman says the issue mainly comes down to immigration policy. The ONS estimates that 69 per cent of projected population growth to 2031 is attributable to future net inward migration. The latest figures assume a long-term net inflow of 190,000 people annually, up from 145,000 a year previously.
The argument for immigration has been that it helps boost the economy by filling gaps in labour supply. Coleman says this is short-sighted, since it puts off the need to get young people into the labour market. McDougall believes that the UK will need to draw more of its labour supply from older age groups.
But nothing is set in stone yet. As the ONS points out, the assumptions underlying the projections are based on recent and current demographic trends and do not attempt to predict the impact of future government policies, changing economic circumstances or other factors.
The figures also become less reliable the further one looks into the future, it adds. Varying either the fertility or migration assumptions, for example, could increase or decrease population change by half a million by 2016 and about two million by 2031, it explains.
The DCLG is not about to change its housing targets just yet. It intends to wait until more detailed sub-national projections emerge next year before any reassessment is made. The housing green paper target of 240,000 new homes a year exceeds the anticipated household formation rate for the next two decades, it notes. But Coleman claims that the 2004-based figures behind it are seriously out of date.
As has been consistently acknowledged in recent years, there is a significant gap between supply and demand for homes. With an ageing as well as a growing population, the risk is that the gap could get wider, despite the government's best intentions to bridge it.