Office for National Statistics admits it missed an estimated 350,000 in net migration over a decade because of flaws in a key survey
The number of eastern European migrants who came to Britain in the last decade was hundreds of thousands higher than previously thought, the Office for National Statistics has admitted.
In a disclosure that will fuel intense national concern about immigration, the agency said it had failed to count an estimated 350,000 migrants who arrived in this country between 2001 and 2011.
The ONS said the mistake occurred because it used “inadequate sampling” in a crucial survey at airports which is used to estimate net migration - the difference between the number of people arriving in Britain and those emigrating.
It said most of the migrants who were omitted from the International Passenger Survey (IPS) were from Poland and other former Communist states which joined the European Union in 2004, known as the “EU8” countries.
The revised totals showed net migration over the decade increased from just under 2.2 million to more than 2.5 million.
The ONS’s highest additional number of migrants was for 2006, when net migration is now thought to have been 67,000 higher than previously thought, reaching 265,000.
Original estimates were too low because the ONS concentrated its survey on main airports such as Heathrow but ignored migrants who were arriving on a growing number of budget airline routes into smaller, regional airports, a report said.
“There is evidence that shows the IPS missed a substantial amount of immigration of EU8 citizens that occurred between 2004 and 2008, prior to IPS improvements from 2009,” said the document.
“This is evident from comparisons of IPS data with a number of other data sources related to immigration.
“The EU8 migrants were missed due to IPS interviewing being concentrated at the time at principal airports, such as London Heathrow, London Gatwick and Manchester.
“During this time, many migrants from the EU8 countries were travelling on the increasing number of routes connecting their countries with the UK regional airports. Many of these routes were not covered, or not fully covered, by the IPS for migration purposes prior to 2009.”
The number of children migrating to Britain was also underestimated, it added.
More regional airports were included in the IPS from 2008 but the improvements were “too late to capture the main wave of increased migration” folloring EU expansion in 2004.
Labour, which was in power at the time, has admitted it was wrong not to impose restrictions on eastern Europeans’ ability to come to Britain from 2004.
