I do wonder. Consider the following.
Eurosceptics have secured a Conservative promise for a referendum on the question that is the most extreme – and also therefore the question that they are least likely to win on. (And remember that the experience of referendums around the democratic world over the years is that the status quo option usually gains in support as polling day nears.)
They’ve also done so in a way that will result in the leader of their own party campaigning against them, along with all of the Cabinet (if the Tories are in power, but of course if they’re not then this week’s ‘victory’ becomes irrelevant).
A triumph? Or a result that, if it comes to be, will see their own party split and fighting their corner on the least favourable grounds? Most people would call that a blunder, not a success.