New migrants to Scotland are set to outstrip the number of babies born within the country by nine to one over the next ten years, according to new figures from the Office of National Statistics (ONS). Overall, the UK’s population is expected to grow by nearly 10 million over the next 25 years, with the majority of new arrivals settling in England. However, the estimates are based on figures recorded before the migrant crisis, and are therefore likely to be a gross underestimate.

For the UK as a whole, the ONS has estimated that the population will grow by 9.7 million over the next 25 years, from an estimated 64.6 million in mid-2014 to 74.3 million in mid-2039. 51 percent of the assumed increase comes from net migration, whereas the rest is expected to come from births within the country.

“Because immigration is concentrated at young adult ages, the assumed level of future net migration has a more immediate effect on the projected number of women of childbearing age and hence the projected number of births,” the ONS said.

Focussing in on Scotland, the ONS has suggest that around 14,000 people will arrive in Scotland per year for the next decade, two thirds of whom will come from outside the UK. That equates to nine new arrivals to the country for every baby born in Scotland.

The figure actually falls below the Scottish government’s target of attracting 25,000 newcomers each year, and represents a downgrade on previous population projections, Herald Scotland has reported.

However, the figures may be a gross underestimate. According to the ONS, the projections are “based on the population as of 30 June 2014”, well before Europe’s current migrant crisis got underway. They also only take into account official migration statistics, but do not appear to include any provision for illegal migration, which is notoriously difficult to quantify.

Overall, they have estimated that the UK will experience a population increase of 14 percent by 2039, placing us behind just three EU countries: Sweden and Belgium, which are projected to realise a 21 and 23 percent population growth respectively in the same period, and Luxembourg, which is expected to see a whopping 67 percent growth from half a million people in 2014 to 900,000 in 2039.

But the ONS expects that the European Union as a whole will see just a three percent rise in total by 2039, and for Germany it has projected that the population will fall by three percent in the same period, from 80.7 million in 2014 to 78.1 in 2039.

Yet Germany is on track to receive in the region of one million people this year alone, representing a 1.2 percent population increase in just one year.

The ONS itself has admitted to scaling down projections to give a more conservative estimate, by assuming that net migration will run at 198,000 a year over the 25 years, well below the current rate of 330,000 a year. In order to achieve that projection, it has assumed net migration will fall to 196,000 by 2020, the year David Cameron has promised to get the figure under 100,000.

Guy Goodwin, director of social and analysis at ONS, argued that his organisation needed to err on the side of caution, saying: “There is a risk that if we take the latest figures and project those forward we get figures that prove to be way out. We always look at longer term trends.”

However, even the ONS’s official projection is cause for concern as services already feel the strain of so many new arrivals. Lord Green of Deddington, chairman of Migration Watch UK, said: “These projections confirm that our population will increase by more than twice the population of Birmingham in the next five years.

“The prospect of nearly 10 million in 25 years underlines the huge impact on housing and public services, unless the government succeeds in bringing net migration right down.”