The population of England and Wales has grown by 3.7m, or 7%, in a decade, to 56.1m according to the 2011 Census.
The Office for National Statistics figures, released on Monday morning, also revealed the percentage of people over 65 is at the highest of any census, at 16.4%.
Nearly half a million are over 90, at 430,000 residents compared to 340,000 in 2001.
The ONS results show that every region in England and Wales had a larger population in 2011 than 10 years earlier.
But not everything has changed. According to the ONS the average household size is still 2.4 people, the same as it was in 2001.
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 areas that saw the largest growth were the London boroughs of Tower Hamlets, which has grown 26.4% in 10 years, and Newham 23.5% since 2011, and Manchester (19%) in the North West.
The areas that saw the smallest growth included Barrow-in-Furness in the North West which has declined by 4% since 2001. Knowsley, Sefton, Sunderland and South Tyneside also saw declines in population, as well as the London borough of Kensington and Chelsea.
ONS will release figures for ethnicity and race later this year, however the upsurge could lead to fears that the UK's population is growing too quickly or the rate of immigration is too high.
In a blog for the Huffington Post UK, Sunder Katwala, head of the think tank British Future, said some concerns over Britain's population were mainly about immigration with "population being used as a slogan."
"Instead of declaring Britain closed, we should spread growth and jobs around Britain, just as we’ve regenerated Stratford to host the Olympics, and turned around the population decline in the centre of great cities like Manchester and Liverpool."
Glen Watson, Census Director said: "The whole operation has worked well. We met our targets both for response and quality. We’ve had fantastic support from the public, and also from voluntary groups, community groups and local authorities throughout England and Wales.
"I’d like to say a big thank you in everyone involved, including the 35,000 people who worked on the data collection and helped to make the census a success."
Matt Cavanagh, IPPR Visiting Fellow, said the rate of increase was "broadly similar to the rate of increase between 1910 and 1970, and only half the average rate of increase between 1801 and 1910."