The population of the UK has increased by more than half a million - the biggest rise for 70 years - according to official figures.
There were 65,648,000 people in the UK in June 2016, according to the Office for National Statistics (ONS).
The ONS said that was a rise of 538,000 on the figure in 2015, equivalent to a city the size of Bradford.
Net migration of 336,000 accounted for 62.4%, while the difference between birth and death rates made up 35.8%.
There was also an increase of 9,500 in armed forces personnel based in the UK.
The population went up in 364 local authority areas, with the biggest rises in the City of London (7.3%) and Tower Hamlets (3.3%).
It fell in 26 areas, including South Lakeland and Aberdeen, 17 of them on the coast, and remained the same in one.
Last year's increase was the highest since 1947, which saw a rise of 551,000, driven mainly by a surge in births after World War Two.
Around the UK, the population of England jumped by 481,800 (0.9%) to 55,268,100 - and is now more than 55 million for the first time.
The population of Scotland increased by 31,700 (0.6%) to 5,404,700, Wales by 14,100 (0.5%) to 3,113,200, and Northern Ireland by 10,500 (0.6%) to 1,862,100.
Neil Park, head of the Population Estimates Unit at the ONS, said: "The population of the UK continued to grow in the year to mid-2016 at a similar rate to that seen over recent years.
"Net international migration continued to be the main driver, but there was also an increase in births and fewer deaths than last year."
The population of the UK has increased by just over five million in 11 years - previously it took 35 years, from 1970 to 2005, to make the same leap.
Population change in the UK has averaged 482,000 a year over the past decade.
The ONS bases its figures on the usually resident population of the UK, and long-term international migrants who change their country of usual residence for a period of 12 months or more.