The government can’t say with accuracy how many visa overstayers there are in Britain – no data has been collated for five-and-a-half years.

Sky News has spoken to immigration lawyers about the numbers, and one believes there could be as many as 400,000 living across the country.

Why doesn’t the government know?

The Home Office used to gather data on visa overstayers by effectively checking a list of passport numbers associated with visas against a list of passport numbers of people leaving the UK, taken from airlines and other international travel providers.

If there was a passport number match in the arrivals and departures part of their database, that person was recorded to have left when they should have. If there wasn’t, they were a potential overstayer.

They stopped producing the figures because a combination of Brexit and COVID added complications that made the Home Office conclude they wouldn’t be able to get to a reliable number using the same method.

It’s now four and a half years since EU citizens had freedom of movement to the UK revoked, and more than three and a half years since pandemic-era travel restrictions ended.

And yet we are still waiting to see what a new method might look like.

The old method wasn’t perfect. If someone changed their passport while in the UK, for example, or if the airline or individual entered the number wrong when they were leaving, there wouldn’t be a match.

The Home Office regarded the statistics as likely overestimating the true number of overstayers, and the Office for National Statistics designated the figures as “experimental” rather than “official” statistics, meaning the conclusions should be treated with caution. But they were a reasonable best guess.

With all that in mind, between April 2016 and March 2020 upwards of 250,000 people were flagged as potential overstayers, equivalent to 63,000 per year.

That’s more than the 190,000 people who are recorded to have arrived in the UK on small boats since 2018.

It represents 3.5% of the seven million visas that expired over that period, so at least 96.5% of people left when they should.

Other Home Office data reveals that more than 13 million visas were issued between 2020 and the end of June 2025, including a record 3.4 million in 2023.

But what we don’t know is how many have expired, which means it’s difficult for us to even guess how many people might have overstayed.