The population of England and Wales has leapt by 3.7 million over the last decade, the biggest growth between censuses since records began, according to new figures.
The number of people living in England and Wales stands at 56.1 million, a rise of just over 7% on the 52.4 million registered in the 2001 census.
The growth in population was fuelled by migration, increased life expectancy and a rise in fertility rates, the Office for National Statistics (ONS) said.
The new figures show the biggest growth in numbers in any period between censuses since the headcount began 210 years ago in 1801, with England now the fifth fastest growing country in the European Union.
The ONS said the figures showed that the population for England and Wales was just under half a million higher, or 480,000, than was previously estimated.
The figures also showed an ageing population, with more over-65s than ever before, with one in six now in this age group in England and Wales. Of these, 430,000 were aged 90 more.
The figures are from the first wave of data to be released following the 2011 Census held on March 27 last year, the biggest conducted so far.
There are now 900,000 over-65s in England and Wales, with growth in the over-90 age group "particularly strong", according to the ONS. There has also been an increase in the number of people in their 20s and an increase in the number of young children, it said. There are over 400,000 more under-fives compared with 2001, partly reflecting a rise in the number of women of child-bearing age because of inward migration, the ONS said.
Around 55% of the growth in population, or 2.1 million, between 2001 and 2011 was the result of net migration, the ONS said, with 45%, or 1.6 million, attributable to increased life expectancy and fertility rates. The ONS results showed that every region in England and Wales had a larger population in 2011 than 10 years earlier.
Over half of the population growth was in London, the South East and the East of England. The largest increase in population was in London, which grew by 12%, gaining more than 850,000 inhabitants and taking its total population to more than eight million. The local authority with the fastest growing population was Tower Hamlets in east London which registered a 26.1% population rise in the last decade, followed by the east London authority of Newham at 23.5%. Manchester registered the third biggest population growth by local authority at 19% since 2001.