The UK's population is at a record level, with it increasing by almost half a million to 64.6 million within a year, according to the latest official figures.
The increase between mid-2013 and mid-2014 included net immigration of 259,700, the Office for National Statistics said.
Over that period 582,600 migrants arrived in the UK, compared with just 322,900 people leaving the country.
An ONS spokesman said the statistics meant the UK population, had grown by almost half a million since mid-2013, up 0.77% to 64,596,800 - higher than the annual increase of three quarters of a per cent seen over the last decade.
The number of births occurring in the year to mid-2014 was down compared to that seen in the previous year, continuing the downward trend seen since the recent peak in mid-2012.
The estimated population of England in mid-2014 was 54.3 million, up 0.84%, with the corresponding figures for Scotland standing at 5.3 million (up 0.37%), compared to 3.1 million in Wales (growth of 0.31%) and 1.8 million in Northern Ireland (up 0.59%).
The overall increase was due to natural growth of 226,200 and a net migration of 259,700, while an increase of 5,200 was due to other changes and adjustments, mainly in the armed forces.
The figures also show that net international migration in the year to mid-2014 was the highest since the year to mid-2011 and up by 76,300 from 183,400.
Migration accounted for 53% of the total increase.
Over the period, the median age of the population was 40, the highest ever estimated, with the proportion of older people continuing to rise.
There were more than 11.4 million people aged 65 and over, up from 11.1 the previous year.