David Cameron wants a ‘definitive’ victory in this referendum, one that will settle the question of Britain’s EU membership for a generation. But, increasingly, I doubt whether this referendum will resolve things for that long. A second referendum within a decade now looks likely, as I argue in the magazine this week.

So, why do I think a second referendum looks likely if In wins? Well, leaving the EU used to be a relatively fringe position in British politics. Most Eurosceptics said that they wanted reform rather than for Britain to leave outright and there was no one in the Cabinet who openly backed getting out. But that has now changed. There are more than 130 Tory MPs campaigning for Brexit, including five cabinet ministers. It is more likely than not that one of these will be the next leader of the Tory party, and Prime Minister. Whatever the result of the referendum, Out is now a mainstream political position.

Another reason why a second referendum is likely is that the EU is in flux at the moment. There is a chance that the Eurozone could decide to integrate further which, if it led to Eurozone caucusing, would have profound implications for the UK. Or, the European Court of Justice, which has a very expansionist view of its role, could take decisions that this country finds intolerable.

Of course, there are still five weeks to go until the referendum and events could change the dynamic of the campaign and swing things Out’s way. But at the moment, a victory for In looks more likely than not. But it is unlikely to settle things for more than a few years. This will be particularly true if the next Prime Minister is an Outer.