The UK population could hit 70million three years earlier than expected if migration does not fall, according to ‘alternative’ official estimates.
The number of people living in Britain is due to top 70million by mid 2029 under the main forecast.
But ‘variant’ predictions highlighted by the Office for National Statistics (ONS) today suggest that if net migration remains at its current level of around 246,000 the figure could be reached by 2026.
The details underline the impact of migration on the rising population.
The ONS bases its population forecasts on assumptions about the future that are regarded as best reflecting trends. To help account for potential mistakes, it prepares figures with alternative assumptions about fertility, mortality and migration
The most recent population estimates released by the ONS last month suggested that 46 per cent of growth in numbers will be down to births outstripping deaths, with 54 per cent attributed to net international migration.
Taking into account babies born to foreign parents in Britain, immigration is indirectly expected to account for 77 per cent of the growth.
The ONS bases its forecasts on assumptions about the future that are regarded as best reflecting trends.
However, the body admits that the data contain ‘inherent uncertainty’ and will ‘inevitably differ to a greater or lesser extent from actual future population change’.
To help account for potential mistakes, it prepares figures with alternative assumptions about fertility, mortality and migration – although it stressed they are not considered the most likely outcomes.
The main ONS projection assumes that international net migration to the UK progressively falls to reach 165,000 per year from mid-2022 onwards.
But a ‘high migration’ estimate, proposing that immigration remains at its current level of 245,000, speeds up population growth significantly.
Instead of hitting 70.1million in 2029, the mark is passed in 2026.
‘In the principal projection, the population is projected to reach 72.9 million by mid-2041,’ the ONS report said.
The central ONS forecast, published last month, assumes that migration falls to 165,000 a year by mid-2022, and the population will pass 70million in 2029
The number of people living in Britain is due to rise by 3.6 million – 5.5 per cent – in a decade
‘In the high migration scenario, population growth is considerably higher than in the principal, with the population projected to increase to 75.4 million by mid-2041.’
Another ‘low migration’ scenario, where net inflows fall to 85,000, has the population staying below 70million until 2037.
‘Overall, the migration variants have the largest effect on the principal projection, when compared with the fertility and life expectancy variants,’ the ONS report said.
New net migration figures are due to be published later this week.
The last set for the year to March came in at 246,000 – including 127,000 arrivals from the EU, 179,000 from the rest of the world and 60,000 people leaving the country.
Overall, the population is expected to grow more slowly than at the last forecast in 2014 because of lower immigration, women having fewer children and a slow down in the growth of life expectancy.