By 2043, the population will have swollen to more than 74 million, outstripping France and Germany.
Two thirds of the expansion will be due to immigration, according to the Office for National Statistics.
The landmark figure of 70 million could be reached in 16 years after officials yesterday revised upward population projections.
Over the next decade, the population will increase by the equivalent of a city the size of Leeds every year. Officials estimate the population will swell by 0.8 per cent–or 491,000–every year to 2020, the fastest sustained growth since the 1960s.
It is a fresh headache for David Cameron who has pledged to bring immigration down to the “tens of thousands”.
The trend also means extra pressure on public services and resources as the number of pensioners soars.
Sir Andrew Green, chairman of the campaign group Migration Watch UK, said: “These figures confirm that the UK’s dramatic rise in population will continue unabated.
“The population is now set to hit 70 million in 16 years’ time, over two thirds of which is due to immigration.
“As people return home this evening crammed into public transport and on congested roads, they could well ask where all of these people are going to fit.”
The ONS revises its population projections every two years to take into account changes in immigration, fertility and life expectancy.
It now predicts the country will have 70 million people by 2027, compared with 2029 at the last estimate. The population is currently around 62 million.
Crucially, if the trend continues, it will overtake Germany for the first time as the largest EU country by 2043.
It would mean the UK is the biggest country in Europe outside Russia.
It will grow by 10.9 million people by 2035, of which two thirds Continued from Page 1
will be driven by direct immigration or by migrant mothers giving birth.
The latest long-term assumption for annual net migration–the number of people coming to the UK less the number leaving–is 200,000 a year.
Average life expectancy will also rise from 78 to 83 for men and from 82 to 87 for women.
Damian Green, the immigration minister, said: “We have made sweeping changes to get a grip on immigration, closing down routes subject to abuse and taking action against those with no right to be here. Much has been done but there is more to do to bring down net migration to the order of tens of thousands a year and ensure migration which benefits the UK.”
The population is projected to become older with numbers in the oldest age groups rising the fastest. There were 1.4 million people aged 85 and over last year, but this is expected to double to 3.5 million by 2035. The number of people aged 95 and over will more than quadruple while centenarians will rise from 13,000 to 110,000 in 2035.
The baby boom immediately after the Second World War and in the 1960s will increase the number of people of state pension age by more than a quarter, from 12.2 million to 15.6 million by 2035, the ONS said. As a result, the ratio with workers will fall from 3.16 people of working age for every person of state pension age in 2010 to 2.87 by 2035.
Steve Webb, the pensions minister, said: “These figures show that life expectancy in Britain continues to increase dramatically and that is why we took the decision to raise the state pension age.
“We cannot continue to pay the state pension at an age set early in the last century and leave our children and grandchildren to pick up the tab.”