Britain will become the most populous country in the European Union within a generation, thanks to the fastest population growth since the baby boom.
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.
The ONS now predicts the UK 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 will be the biggest country in Europe outside Russia.