evidence: Looking at first-generation migrants, there are about 650,000 people in England, Wales and Scotland born on the island of Ireland. Subtract the number of people who already have an Irish passport and you get about a quarter of a million. Then we come to Northern Ireland. There may be people there who would choose not to take up Irish citizenship for any number of reasons, but if we focus just on the entitlement to an Irish passport and again subtract those who don't already have one, that's another 1.3 million people. That means about 6.7 million people in the UK who don't already have an Irish passport who could be entitled to one. We think that's a conservative estimate, but it's still quite a lot more than the current population of the Republic of Ireland, which is 4.8 million.