EU ExitChange is afoot in eurosceptic circles, starkly illuminated by Douglas Carswell’s appearance on the Spectator’s weekly podcast.

It’s causing waves, because the headline is that Carswell says he was wrong to rebel – having just taken his name off the two Immigration Bill amendments.

Those in UKIP ranks who are always keen to enter a purer-than-thou competition are duly making out that the arch-rebel has sold out and abandoned his commitment to leave the EU. It’s not just untrue, it’s a laughable conspiracy theory (one even suggested to me this morning that Douglas had been won over by the offer of a PPS job – try imagining for a moment the Government making such an offer, still less Carswell being tempted by it).

Instead, this is a sign of an important change going on among prominent anti-EU figures. Carswell hasn’t stepped back one bit from his Better Off Out views – as he made clear in a blogpost explaining why he was no longer backing the Mills and Raab amendments:

“If we want to restrict the free movement of people into Britain from the European Union, then there is only one thing we can do; Leave. No amendment. No motion of the House of Commons. No ministerial initiative or decree will change that. If you belong to a club that has a rule that says there is to be free movement, you had better leave the club if you don’t want it.”

That’s a coherent and correct position – ironically, it’s also the position of those UKIPers who are attacking Carswell today, which says rather more about their tribalism than it does about his principles.

The change occurring is this: a new generation of anti-EU politicians and activists are sick of messing around, they want to win this battle once and for all.

It’s a shift from the old cavalier model of euroscepticism – grabbing attention regardless of whether it gets us any closer to the EU exit door – to a tougher roundhead position which prizes victory for the cause above all else.

To Carswell, and a generation of younger opponents of the EU, the idea of the Mills amendment may be laudable but in practice it is merely “parliamentary posturing” – by implication, posturing used by some to look eurosceptic without actually declaring themselves Better Off Outers.

It’s unsurprising that some in the eurosceptic movement don’t like this. It’s a direct challenge to the futile approach that has signally failed to secure Brexit over the last 40 years, it’s completely at odds with the personalities of some of those involved (Nigel Farage is the ultimate cavalier in this context, right down to his rhetorical ruff) and – most importantly – its logic leads inexorably to the conclusion that a Conservative majority in 2015 is an essential requirement to leave the EU.

No doubt each of those points will have raised some eyebrows, and in some cases howls, but the last is the most controversial.

It boils down to a simple pair of questions.

1) How will Britain leave the European Union? 

It won’t be through the sudden exposure of some silver-bullet conspiracy theory. It won’t be by a UKIP parliamentary majority triggering Article 50 (or at least not this century). It will be by a referendum if it happens at all.

2) How will we get that referendum?

Not by electing a handful of UKIP MPs in 2015 at the same time as propelling Ed Miliband into Downing Street. Nor by that fantastical UKIP majority in 2015.  We might wish there was a power of popular initiative to force a referendum, or that Labour and the Lib Dems will see sense on the people’s right to have a say, but neither will happen any time soon. It can only come about by the Conservatives winning the 2015 General Election – for all the justified anger and distrust over the “cast iron” promise of a referendum on Lisbon, there is no way Cameron’s MPs or party members would allow him to avoid holding an in/out vote if he won next time round

That is the cold, hard reality of the situation and we must deal with things as they are.

Carswell’s point is that while it is fun to rebel, and while many of those doing so are there for the right reasons, every time MPs do so they harm Tory chances in 2015. In so doing, they make it less likely we will leave the EU. He feels that freeing Britain from the EU is more important than rebellion for its own sake.

The flamboyance of the cavalier may be attractive, but it is the steel and determination of the roundhead which will actually get the job done.

It’s a challenge to eurosceptics: do we want to tick boxes to prove our purity, or do we want to actually win this great battle for our freedom? I know which I prefer.