Are ‘Channel migrants’ 24 times more likely to go to prison than British citizens?

New analysis from the Conservative party has claimed migrants who cross the Channel in small boats are 24 times more likely to go to prison than the average British citizen.

This claim was first reported by The Times last week and was also covered by the Daily Express, GB News and MailOnline. It was also made by the Conservative party press office and shadow home secretary Chris Philp, who claimed the analysis showed small boat arrivals were “much more likely to commit serious crime” and were “a danger to the public”.

We’ve repeatedly asked the Conservatives about their research but at the time of publication have not received a response, so we don’t have full details of their calculations.

But based on the details reported, the figure for how much more likely “Channel migrants” are to go to jail is not reliable. Most notably, that’s because the estimate compares 2025 prison data to 2021 population figures that are likely out of date, and appears to use data on the imprisonment of foreign nationals in general without considering whether people of a specific nationality who arrived via small boat crossing may be more or less likely to go to prison than their compatriots overall.

Some of the details in the reports last week were also not accurate. After being contacted by Full Fact, the MailOnline corrected a line in its story claiming that “official data” showed “a whopping 3.4%—one in 30—small boat migrants end up behind bars”.

The University of Oxford’s Migration Observatory says there is no reliable publicly available data on the proportion of small boat arrivals who go to prison.

Political parties should ensure they back up their claims with evidence and if claims are based on figures, the party should be transparent about sources and calculations.

Where does the Conservative figure come from?

The Times article says the Conservative analysis is “based on the 10,838 foreign criminals” in prison in England and Wales in March 2025.

Ministry of Justice (MoJ) figures do show that on 31 March 2025 there were a total of 10,838 “foreign nationals held in custody” (a figure which excludes dual nationals). Of these, 61% were serving a sentence, with the remaining 39% either on remand (including 2,702 people awaiting trial) or in prison for non-criminal reasons, such as a civil or immigration offence. (This means not all of the 10,838 foreign nationals in custody are necessarily “criminals”.)

These figures only show the number of foreign nationals in prison at any given point in time, so can’t reliably tell us how likely it is for a foreign national to go to, or have been to, prison at some point. They also do not include foreign nationals who have been convicted and jailed but subsequently returned to their home country while serving their sentence.

The Times story goes on to say that the March 2025 prison data suggests that the rate of British citizens in jail is 0.14%, compared with 0.18% for foreign nationals, and that the rate is “significantly higher for the nationalities who make up the largest small boat arrivals, including Somalians, Afghans, Iraqis, Albanians and Iranians”. The Times says the Conservative analysis suggests “some 3.4% of small boat migrants could go to prison”, and that this is 24 times the 0.14% British citizen imprisonment rate.

It is not clear from the Times how exactly the 3.4% figure was calculated, however—we don’t know for sure all the nationalities it covers, what proportion of small boat arrivals those nationalities account for and over what period, or how else the figures may have been adjusted. (Mr Philp’s X post referred to the 3.4% being a “weighted average”, but we don’t have any further details.)

Population data used to calculate imprisonment rates is from 2021

The Times story makes it clear that the imprisonment rates for specific nationalities were calculated by dividing the number of people of each nationality in custody as of 31 March 2025 by the total number of people in England and Wales who held a passport from that country as of the 2021 Census (excluding those who also held a British passport).

This calculation takes no account of how the population of different nationalities in England and Wales may have changed since 2021. In recent years there have been significant changes to migration patterns to the UK (including a substantial increase in migrants arriving both via legal routes and by small boat crossing) and some people’s categorisation may have changed (for example, they may have since gained British citizenship). So the 2021 Census figures may not accurately reflect the numbers of each nationality in England and Wales as of 2025.

For example, Census data shows that in 2021 there were an estimated 2,133 Somali passport holders in England and Wales (excluding those who were also British citizens). Yet government statistics show that between 2022 and March 2025 a total of 1,430 Somalis arrived in the UK via small boat crossing.

Indeed, far more small boat crossings have taken place since 2021 than in the few years before, meaning most small boat arrivals since larger numbers began entering the UK via this route in 2018 are not captured in this Census data.

It’s therefore not possible to reliably calculate the proportion of foreign nationals in prison in 2025 based on population figures from 2021.

The Migration Observatory told Full Fact: “Getting accurate data on criminal conviction rates by nationality is very hard because the UK currently does not have accurate population data for each nationality.

“The migrant population has changed significantly since 2021… and more recent population estimates are highly uncertain due to data collection issues. Some groups of migrants are particularly likely to be undercounted, such as Albanians.”

We don’t know if small boat arrivals are more or less likely to go to prison than their compatriots

Importantly, the prison data used in the Conservative analysis appears to refer to all those of each nationality in custody, not only those who arrived via small boat. (For example, the Times states that there were 258 Somalis in prison at the end of March—the data shows this is the total number of Somalis in custody.)

We don’t know how many of the foreign nationals held in custody do not have the right to be here, how many are on a valid visa, and how many have indefinite leave to remain or another status. As the Home Office noted in its response to the Conservative analysis, these figures could also capture foreign nationals who were placed in custody while here temporarily (for example, while on holiday).

The Conservative party analysis appears to assume that small boat arrivals are jailed at the same rate as others of the same nationality who have arrived by another route.

But we don’t know whether or not this is the case.

The Migration Observatory told us: “While we cannot know precisely what share of people from different countries are incarcerated, it is clear that the numbers do vary considerably by nationality. A key reason for this is likely to be differences in socio-economic status among people arriving on different immigration routes.

“For example, people from comfortable backgrounds with high levels of education and professional jobs are much less likely to go to prison, and this is likely to be true among migrants too (such as those arriving on work visas for skilled jobs). Age and sex also play a role: young men have higher offending rates.

“As a result, it would not be surprising if people arriving in the UK through different routes (eg, on work visas versus small boats) had different offending rates, though the data are currently not good enough to understand these trends properly.”

A Home Office spokesperson said: “The comparison of these two data sets is completely unfounded.

“It is inappropriate to apply foreign imprisonment rates to small boat arrival data as these consist of very different groups of people.”

The MoJ told us that it does not currently collate data that would identify how foreign nationals in custody arrived in the country, or their immigration status (beyond figures for the number issued with an immigration detention order). It noted though that the justice secretary has asked civil servants to review what more data can be published (similar work is also being carried out at the Home Office).

Because of the uncertainty and lack of data outlined above, we’ve not attempted to produce any alternative estimates here.

What other data do we have?

As we’ve written before, official or other reliable data on migration and crime is very limited.

The Migration Observatory told us that previous studies looking at the impact of migration on crime rates showed no relationship between immigration and violent crime rates in England and Wales, though a study published in 2013 found that a rise in the asylum seeker share of the population in the early 2000s led to an increase in the rate of property crime.

It told us these studies did not look at whether any change in crime rates was directly caused by migrants or by non-migrants, however.

And these studies were published some years ago, prior to the UK leaving the EU, meaning that they don’t take into account the impact of recent changes in the nature of migration to the UK, and so can’t be used to draw conclusions about migrants who have arrived via small boat crossings more recently.