The Sun has spotted a discrepancy between the estimated number of arrivals and the number registering to work – but there are explanations for this

“The Great Migrant CON: Government Cover-up Fury,” says the splash headline in Friday’s Sun. The article says: “630,000 registered to work here in 2015. Official stats say just 257,000 came from the EU … One expert said the government appeared to be ‘deliberately keeping voters in the dark’ to boost its chances in the in/out referendum.”

Is there any truth in it?

The Office of National Statistics published its latest quarterly migration figures on Thursday showing that the headline net migration figure fell quarter on quarter for the first time in nearly two years. The Sun chose not to report this and instead focused on the alleged cover-up.

The ONS figures showed that 257,000 EU nationals came to live in Britain in the 12 months to September 2015, and 630,000 EU nationals were issued with national insurance numbers in the 12 months to December 2015.

That is a big discrepancy. What’s going on?

It has been well known that for the past 10 years the number of national insurance numbers (Ninos) issued has been far higher than the levels of immigration shown in the quarterly ONS figures, which estimate the number of migrants based on the International Passenger Survey. Anti-immigration campaigners such as Migrationwatch have often cited the Nino numbers in preference to official migration statistics.



In December Jonathan Portes, a former chief economist at the Department for Work and Pensions, highlighted the discrepancy in a blogpost in which he examined David Cameron’s assertion that 40% of EU recent migrants claimed benefits. He said it was important that the government should throw some light on the issue and “not conceal the facts”. This is the source of the Sun’s cover-up claim.

So is it right?

No. In its latest release the ONS tried to explain some of the possible reasons for the discrepancy. They include:

• Nino registrations may be weeks, months or years after a migrant has arrived in Britain. The 630,000 figure includes 170,000 new Ninos issued to Romanians in Britain. The ONS say that at least a third of these – more than 50,000 – involved Romanians who were already living in Britain but used the lifting of restrictions on them to enter the labour market legally. This would also apply to other migrants who may have been working in the hidden economy.

• The total number allocated a Nino is not the same as the number of non-UK nationals working in the UK. “They may have subsequently left the UK, or they may still be in the UK but have ceased to be in employment.” This is particularly true of the large but unknown number of those who come to Britain for short-term employment, for example in the food processing industries, and then go back home. This short-term migration is not picked up in the net migration figures, which are estimates of people who come to live in Britain for more than 12 months.

• Nino fraud. This is not cited by the ONS, but the National Audit Office has in the past documented widespread fraud in national insurance numbers, with multiple applications particularly for use in identity theft.

What’s the verdict?

These factors tend to make the Nino figures highly unreliable as measures of migration flows. However, Portes has a point when he says there needs to be more light shone on the discrepancy. In particular, publishing data on the number of “active” national insurance numbers would increase trust in their accuracy.

But until that happens they can’t simply be substituted for the official migration figures by newspapers that don’t like the fact they are going in what they consider to be the wrong direction.