The Big Question: Why is the UK's population growing so fast, and is this a good thing?

Why are we asking this now?

Projections released by the European Commission this week suggest that in 50 years time, Britain's population will look very different to how it does today. As part of a broader set of predictions of EU-wide trends, the statistical research body Eurostat found that Britain's population would grow significantly, to become the largest country on the continent, at the same time as getting a good deal older. Figures released by our own Office for National Statistics confirm that important changes are afoot: in 2007, the body found, people aged over 60 outnumbered children for the first time.

How much bigger is our population going to get?

Today, the UK's population stands at around 61 million; after steady decade-on-decade increases, we will be a country of approximately 77 million by 2060, Eurostat estimates.

How does that compare to the rest of Europe?

Four countries will grow at a faster clip than the UK – Norway, Luxembourg, Ireland and Cyprus. Of countries of a comparable size, though, no other will grow at such a rate. Spain will grow by about seven million to 52 million, while France will see a rise of more than 10 million to 72 million; Germany, the biggest at the moment, will see its population decline by a precipitous 11 million to 71 million. Italy and Poland are expected to suffer similar decreases.

The EU as a whole will see a rise of just 10.3 million, which means that if Britain were excluded, the European population would actually fall.

Why is Britain growing faster than other countries?

Britain will see a significant increase in migration, but that's also true of countries like Spain, Italy and Germany. The real difference is likely to come in the UK's increasing typical life expectancy and birth rate, which experts trace to higher standards of living: when an economy is healthy and state support in forms like the NHS and child care are in place, fertility rates and life spans tend to rise. Britain is expected to see a natural increase in its population without immigration of 7.7million. Apart from France, with an increase of 5.5 million, the next biggest rise is Norway's 610,000, and most other countries will see their birth rate in decline.

Are these figures reliable?

It is notoriously difficult to make accurate population predictions. "It's important to be aware that these projections are speculation based on previous behaviour," says Jill Rutter, a senior research fellow in migration at the Institute for Public Policy Research. "We've got it very wrong before."

Rutter points out that in 1965, British statisticians estimated a population of 75 million by 2000. Because such estimates rely heavily on current trends, there is obviously a large margin of error as the continent's circumstances change over the next few decades: if, for instance, the British economy were to go into long-term decline, the figures would be likely to look very different. Still, the estimates are based on our most up-to-date current understanding of how population increases work, and they are generally accepted as a good best-guess.

So should we be concerned?

Many people are. An ageing population will dramatically change the balance between people of working age and pensioners: today's nine million over-65s will swell to 19 million by 2060, an increase from 16 per cent to 24 per cent of the total population. At the moment, there are four workers for every pensioner: in 2060, there will be just two. Providing for those pensioners will inevitably be a high priority for the government of the day. The island becoming increasingly crowded will also put an additional strain on housing stock – an impact we are already beginning to see as the Government agonises over how to encourage housebuilding in a poor economic climate. There will also be extra pressure on our public services, above all, of course, on the NHS, which is bound to be worked hard by so many extra pensioners.

More people will have a greater environmental impact, too, as they consume more resources. According to Rosamund McDougall, policy director at the Optimum Population Trust, "This population growth is absolutely unsustainable, in environmental terms, energy terms and food production. It will make life for British citizens significantly worse. Even if we comprehensively greened our lifestyles, the UK could only support 27 million people – less than half its present population – from its own resources."

What should we be positive about?

Well-managed immigration that brings in workers with the right skills should be able to offset the impact of the new pressures on public services and the increasingly aged natural population. And being the largest country on the continent provides a competitive advantage that other European countries will envy. The problems the UK will face as a growing nation will probably seem insignificant to Poles who have seen so many skilled workers leave the country for London, for instance.

How will the demographic changes affect British culture?

An influx of skilled foreigners will mean that people who barely encounter immigrants at the moment will be obliged to adapt, as our public services come to rely more and more on newcomers to keep them running. At the same time, an ageing population will likely offset what many perceive as a cultural obsession with youth at the moment: in the workplace, too, ageism will become a totally unviable mindset for employers.

What should the Government do to prepare for such big changes?

The IPPR has called on the Government to try to redefine the public conversation on immigration through such measures as a museum of migration, aiming to make people more comfortable with the idea of foreigners filling skills gaps and making the argument for migrants as a crucial part of a successful nation in the future. And as people live healthier lives for longer, to avoid increasing number of pensioners causing a strain on the welfare system, there may be an increased onus on people to provide a greater share of their retirement income through private plans.

It is also likely that the retirement age will increase – two years ago the Government estimated that it would be 68 by 2050.

Help The Aged argues that an ageing society should not be seen as a problem. "Changes to our population are inevitable over time," says spokesman Mervyn Kohler. "This is a fact of life which should be welcomed and embraced, not treated with concern."

Should we worry about an ageing population?

Yes...

* With fewer workers for every pensioner, the pressure on the state will be severe

* More pensioners will live alone than do now, putting more pressure on housing

* Living for longer will not necessarily mean having more years with a good quality of life

No...

* The retirement age could be higher: we will work longer to offset the pensions shortfall

* Immigrants will help pick up the slack, and may leave the country before they get old

* Being older isn't necessarily a bad thing, and our ageist perceptions will be challenged