The single-largest population surge since records began was revealed on yesterday's census with a baby boom, longer life expectancy and higher-than-expected immigration fuelling an unprecedented jump in the number of people living in England and Wales.
53.1 million people – up 3.7 million on 10 years ago – now live in England and Wales according to the results of the 2011 census released yesterday. Just over half the increase was down to immigration, according to the Office for National Statistics.
The figures also show an ageing population, with one in six Britons now over 65.
The overall population rise is sharper than expected, and means there are 476,000 more people living in England and Wales than previously estimated. This is due to higher-than-expected immigration rates, combined with under-counting at the last census in 2001, the ONS said.
But the country's population boom is by no means evenly spread across the two countries, with over half of the population growth concentrated in London, the South-east and the east of England. In fact, with some notable exceptions such as Greater Manchester, many towns and cities in the north actually saw populations stagnate or decrease.
The census shows that on average 371 people live in every square kilometre of the country, although this figure is skewed by London, where 5,200 residents pack into each square kilometre.
Experts said the census showed that Britain's local authorities are all facing very different challenges.
Matt Cavanagh, visiting fellow at the Institute of Public Policy, said: "It is really only London and the South-east which is crowded, rather than our island as a whole. Today's figures show that some local authorities, particularly in the north, are struggling with the opposite problem.
Simon Ross, chief executive of Population Matters, said: "England faces unsustainable pressure on housing, roads and public transport and green spaces...
"We should give an example to other countries by seeking to limit our numbers."
The census, which was taken on 27 March 2011, showed the biggest population swells were among the very old and very young. There were 3.5 million pre-school children in 2011 – 406,000 more than 10 years earlier – with a 12 per cent rise in this group in the West Midlands.
For the first time ever, one in six Britons is now over 65, while the median age is 39, up from 25 a century ago. The biggest rise was among the over 90s, reflecting the increased longevity public policy makers fear due to demand for health and care services.
In 11 local authorities more than a quarter of the population is aged 65 or over, with the highest being Christchurch in Dorset, with 30 per cent.