Discrepancies between stated number of migrants and national insurance records have fuelled accusations of a pro-EU cover-up. A claimed ‘missing million’ long-term EU immigrants to Britain have been proved to be a phantom army, according to a special analysis by the Office for National Statistics in the run-up to the EU referendum. The ONS says short-term migration – EU citizens coming to Britain for less than a year and sometimes for as little as a month – accounts for recent gaps between the official net migration figures for long-term immigrants to Britain and the number of national insurance numbers issued to EU nationals.