On January 1, the people of Romania and Bulgaria will have the same right to work in the UK as other EU citizens. I know many people are deeply concerned about the impact that could have on our country. I share those concerns.

Ever since the fall of the Berlin Wall, Britain has championed the case for bringing nations which languished behind the Iron Curtain into Nato and the EU. That is important to their prosperity and security – and ours. Britain has also been one of the strongest supporters of a single market. It is in our interests for that it should grow, and for our citizens to have the opportunity to work in other European countries.

But things have gone wrong. Since 2004, we have witnessed the biggest migration in Europe outside wartime. In Britain’s case, 1m people from central and eastern Europe are now living here. So what lessons can be learned? There is the lesson on transitional controls. In 2004, the Labour government made the decision that the UK should opt out completely of transitional controls on the new EU member states. They had the right to impose a seven-year ban before new citizens could come and work here, but – almost alone in Europe – Labour refused it. That was a monumental mistake.