More than a quarter of a million Britons left the UK in the year Labour came to power, new figures show.

Revised data from the Office for National Statistics (ONS) shows some 257,000 British Nationals left the country in the year ending December 2024, compared with an initial estimate of 77,000.

The number has been tweaked after the ONS improved its methods for estimating the number of UK and EU nationals entering and leaving Britain, along with routine updates to data for non-EU nationals.

The data also suggests net migration hit a higher and slightly earlier peak of 944,000 in the year ending March 2023, compared with the previous estimate of 906,000 for the year ending June 2023.

This was followed by a sharper fall than initially reported, with net migration in the year ending December 2024 now estimated to be 345,000, lower than the original estimate of 431,000 that was published by the ONS in May of this year.

Estimates for net migration of British nationals were previously based on the International Passenger Survey (IPS), but this had a very small sample size and had been “stretched beyond its original purpose”, so is no longer considered to be a reliable measure, the ONS said.

The estimates are now produced using more robust and comprehensive data from the Department for Work & Pensions, which incorporates everyone with a national insurance number and which can be used to determine the likely migration status of UK individuals.

Mary Gregory, director of population statistics at the ONS, said: “Understanding the long-term international migration patterns of British nationals has been, and always will be, challenging due to the sheer number of British people crossing the border on a daily basis.

“Very few of these will be migrants and British people don’t need a visa to travel to the UK so we cannot use HOBI data to estimate migration of British nationals.

“Based on these new data and methods, it is clear the IPS continued to underestimate British emigration since 2021 and it also underestimated immigration.”

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