LONDON — Britain’s government runs on numbers — but what if they’re a shot in the dark?
From tepid economic growth to squeezed household incomes, this week’s budget from Chancellor John Healey was packed with grim figures about the state of play in the U.K. — and a host of costly measures to try and turn things around.
Yet it’s almost certain that the budget forecasts Healey relied upon Wednesday will be revised by the time the next fiscal event rolls around.
In this week’s episode of the Westminster Insider podcast, POLITICO unpacked the numbers that govern the U.K. — and found out just how many doubts there are about the information the country relies on.
1. True levels of immigration
Few issues divide Brits like immigration — but grappling with hard data on the issue has proven to be a repeated challenge to governments of all stripes.
For decades, immigration into the U.K. was calculated by the International Passenger Survey (IPS) — essentially people with clipboards at airports, train stations and ports asking people about their intention to stay in the U.K.
The Eurostar platform is pictured at St. Pancras station in London on Nov. 14, 2007. | Cate Gillon/Getty ImagesBut between 2012 and 2020, the number of European Union nationals coming into the country was off by 76% — or 93,000 people a year. The Office for National Statistics (ONS) only discovered this error after trialing a new approach to counting immigration that focused less heavily on the IPS, which was dropped altogether in 2025.
The ONS now uses this new measurement — relying on a combination of Home Office data, information from the Department for Work and Pensions and tax receipts.
But this was again wrong in the year to June 2023 — by 234,000 people.
The original numbers published by the ONS in November 2023 said net migration to the U.K. was 672,000. A year later, the ONS admitted there had been a mistake and said it was in fact 906,000.
Laura Gilbert, who ran data science in No. 10 Downing Street until last year, told POLITICO that net migration numbers are often incredibly misleading — and even the way we calculate those numbers is “highly spurious.”
Gilbert says the quality of the numbers on immigration normally improves months later, sometimes by “quite a lot.” But she warned, “if politicians are making a decision based on exact numbers, often they are using the first number that comes out, which is the worst one.”
2. The scale of unemployment
Healey and Prime Minister Andy Burnham have vowed to get welfare spending down “but in a Labour way.” Much of this will rest on getting young people into work, the subject of a 217-page report by Tony Blair-era minister Alan Milburn.
But Britain’s workforce — and the number of young people out of work — is counted by the Labour Force Survey (LFS), an ONS measurement beset with issues.
For example, between 2019 and 2024, the LFS missed 1 million workers because people with full-time jobs are less likely to answer the phone to surveyors during the week, according to the Resolution Foundation think tank.
The Office for Budget Responsibility (OBR) admitted just this week that the survey is too unreliable to measure productivity. “In recent years, falling response rates have significantly affected the quality of the LFS, making it more difficult to estimate reliably the number of workers and the hours they work,” the watchdog said.
Gilbert says Healey’s claim that there are “1 million young people out of work” is unlikely to be accurate.
The number of NEETs — people not in education, employment or training — is also based on figures from a subset of the LFS, which is particularly susceptible to inaccuracies.
Healey leaves No. 11 Downing St. in London to present the budget to Parliament on Oct. 28, 2026. | Peter Nicholls/Getty Images“I think being within 50,000 on either side of that number is very unlikely to be the sort of level of accuracy that you’re at,” Gilbert said. “It’s entirely spurious, if I’m completely honest, but it’s a big number, you write it down, and everyone reads the papers.”
Ben Warner, who set up 10DS, Downing Street’s data science unit, says the LFS can’t accurately measure the number of entrepreneurs arriving in the country, either, making it difficult for ministers to know if decisions — such as a much-hyped tax relief for founders — are actually encouraging people to come to the U.K.
“I’m willing to bet you a hundred quid [we don’t have accurate numbers] at the level that you would need to make thoughtful policy around this,” Warner said. “I am sure there are people who have very, very good knowledge of the economic statistics. But if you’re a minister, you don’t necessarily have access.”
3. Where inflation and GDP sit
These are hugely important measures for a government: Are costs rising for households — and is the British economy growing?
But buried inside this week’s budget assessment by the OBR was a startling admission: There is a one in five chance inflation in 2027 will come in at over 4.5% … and the same chance it will be under 2.5%. They are profoundly different outcomes for the cost of living, a top political issue.
Warner told POLITICO, “The whole thing is mental. We are discussing the uncertainty of the numbers and pretending that these are real.”
Gilbert says there are knock-on effects at play: problems with net migration numbers and workforce data bleed into inflation and GDP projections.
“Understanding migration tells us about the demographics of the country, and when we look at how many people are in work, and that is wildly undercounted, it looks like there are more people who are unemployed, which has a knock-on effect on GDP and inflation,” she explained.
4. The number of kids on free school meals
The number of pupils in England on free school meals is just over 2.2 million, according to government statistics from the start of this year. That’s more than a quarter of all children in the country.
But Gilbert warns that these numbers are likely to be overestimated because schools “game the system” when census data is collected. “So for anyone who has children in school they may have received a text message that says don’t send them to school with a packed lunch — because the schools get funding based on how many children are on school meals,” she said.
5. The number of rough sleepers on the streets
One of Burnham’s flagship promises when he became prime minister was to end homelessness in the U.K., and Wednesday’s budget put £432 million towards precisely that promise.
Yet the way rough sleepers are counted in the U.K. varies according to each council, with some areas relying on an estimate and others on a street count — sending workers out to physically count the number of people on the streets on a particular day in autumn.
Tents line the side of Euston Road in London on Nov. 13, 2025. | Dan Kitwood/Getty ImagesSome councils have swapped between methods — which can make it look as though they have dramatically reduced their rough sleepers from one year to the next.
For example, in 2017 Brighton and Hove Council used an estimate of rough sleepers which put that number at 176. The following year, the council used a street count — but this took place on a snowy night, so the number fell to 68.
This made it appear as though the number of people experiencing homelessness had been more than halved.