Nearly one in five people in the UK today were born overseas – and one in 25 arrived in the past four years. The true scale of immigration was confirmed when the Office for National Statistics published new figures this week, admitting that population growth since 2021 has been higher than previously thought.

And a study of the data published by the Centre for Policy Studies reveals the rapid pace of change. It warned that the foreign-born share of the population has risen from 16% in 2021 to about 19.6%. The year 2022 saw the fastest rate of population growth since 1828.

There has also been a spike in emigration, with 992,000 British nationals leaving between 2021 and 2024.

And about one in 25 people currently living in the United Kingdom arrived in this same period.

However, the think tank warned that there are still huge uncertainties surrounding the scale and composition of recent migration. It suggested an emergency census might be needed to confirm who is actually in the country.

Centre for Policy Studies director of research Karl Williams said: “This new data shows just how significant recent population change has been.

“The combined effect of record inflows and the sharp rise in emigration has reshaped the country far more quickly than most people realise.

“If decisions on housing, public services and local funding are to keep pace with these shifts, we need a precise and up-to-date picture of the population.”

Home Secretary Shabana Mahmood, who is due to make a major immigration announcement on Thursday, said she is considering “a big increase” in payments for migrants to return voluntarily to their home countries, insisting that the policy represented “value for money”.

She told the BBC’s Political Thinking podcast that she had already directed officials to “pilot a small programme” of increased payments “just to see how it changes behaviour”.

The UK currently offers payments of up to £3,000 for some people with no right to remain in the country who agree to return home.

In plans to overhaul the asylum system set out on Monday, Ms Mahmood said the offer of financial packages to assist with voluntary returns would continue.

But she told Political Thinking the figures involved could increase.

She said: “I haven’t alighted on the full sums involved yet, but I am willing to consider a big increase on what we currently pay.

“I know it sticks in the craw of many people and they don’t like it, but it is value for money, it does work, and a voluntary return is often the very best way to get people to return to their home country as quickly as possible.”

Labour backbenchers have strongly criticised Ms Mahmood’s wide-ranging reforms, which are aimed at deterring migrants from seeking asylum in the UK and making it easier to remove people with no right to be in the country.