Migration drives the majority of UK population growth—exactly how much is debatable

Published: 15th Jan 2020

In brief

Claim

Migration has amounted to 80% of UK population growth.

Conclusion

This combines a rough estimate of both migration to and from the UK and children born to immigrant parents. Without counting children, migration directly accounts for 60% of UK population growth since 2000.

“Migration has amounted to, I think, 80% of the population increase, which is about one million every three years.”

Iain Duncan Smith MP, 15 January 2020

On the Today programme, former Conservative party leader Sir Iain Duncan Smith was asked about the government’s migration plans. He claimed that migration accounts for 80% of the population increase in the UK, amounting to one million people every three years.

Since 2000 the UK population has increased by about 7.8 million. Of that, 4.6 million (60%) is the increase from net migration (the number of migrants coming to the UK, minus the number leaving). In recent years, it’s amounted to around 900,000 every three years and it’s been lower before that.

This is according to the best available figures, though these still carry some uncertainty.

Between 2017 and 2018, the increase in net migration made up closer to 70% of the change in population. Net migration has not directly accounted for 80% of the population increase at any point recently.

So the figures mentioned by Sir Iain don’t appear to refer to net migration alone. However they could refer to research which looks not just at the direct population increase due to migration, but the indirect increase from children born to immigrant parents as well.

This research puts the population increase due to migration at 82% of total population growth—equivalent to roughly a million people every three years between 2001 and 2016.

As we’ve said before, this higher figure shouldn’t be taken as precise, as there isn’t enough data available to reach an accurate estimate of the population of children born to immigrant parents.

It does, however, give an indication of the rough scale if you choose to include children in this way when talking about the impacts of migration.

In any case, given that there are a number of ways to look at these figures, it’s unhelpful to describe this as the impact of “migration” on population growth without any context of what’s being counted.

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