The population of the UK has seen its sharpest annual increase in nearly 70 years, official figures have revealed.
Demographers' latest calculations show there were an estimated 65,648,000 people living in the country at the end of June last year.
Over the 12 months to the middle of 2016, the number of inhabitants rose by 0.8%, or 538,000.
In numerical terms this is the largest increase in population since the year to mid-1947, when it went up by 551,000.
The Office for National Statistics said net international migration continued to be the main driver behind the growth, while there was also a rise in births and fewer deaths.
The figures mean the number of inhabitants in the UK grew by around the equivalent of the population of Bradford in a year.
Natural change - the number of births minus the number of deaths - of 193,000 accounted for just over a third (35.8%) of the overall increase.
Nearly two-thirds (62.4%) was down to net international migration of 336,000.
The population of England grew the fastest, and has now exceeded 55 million for the first time.
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.
"Population growth was not evenly distributed however, with London's growth rate more than twice that in Wales, Scotland, Northern Ireland, and the three northern English regions."
In the 11 years between mid-2005 and mid-2016, the population of the UK increased by just over five million people.
The previous increase of five million took 35 years, between 1970 and 2005, while the five million before that were added over a 17-year period.
Over the last 10 years, annual population change has been on average 482,000.
The ONS figures show that in the year to mid-2016, there were 781,000 births, an increase of 0.7% on the previous year, and 588,000 deaths, a fall of 2.6%.
Net international migration - the balance of the number of people arriving and leaving the country - was at 336,000.
In addition to the direct impact of migration on the size of the population, current and past international migration also has indirect effects on the size of the population as it changes the numbers of births and deaths in the UK, the report said.
England saw the biggest jump in population over the year, with a rise of 481,800, or 0.9%, to 55,268,100. The population of Scotland increased by 31,700 (0.6%) to 5,404,700, Wales saw a 14,100 increase (0.5%) to 3,113,200, and Northern Ireland's population was up by 10,500 (0.6%) to 1,862,100.
The vast majority of local authorities, 364, saw rises in their total population. Of 26 which showed falls in the number of residents, 17 were in coastal areas.
There were 14 areas where population went up by 2% or higher, with eight of those in London.
Statisticians also reported that the UK population continues to age, but at a slower rate than in recent years.
There was only a small change to the proportion aged 65 and over, and an unchanged median age of 40.