I probably shouldn’t be, but I’m quite shocked by the fact David Cameron is proposing a piece of legislation that will, on its own terms, have no effect whatsoever. I mean, of course, his “UK Sovereignty Bill”; this horror would “reiterate” that the British parliament remains ultimate master of its relations with the EU.

But anyone with a passing knowledge of the British constitution should see the flaw here. No parliament can bind its successor; it can at any time repeal or amend anything that was legislated in the past. So the proposed Bill is completely vacuous. Tory Eurosceptics should know this, as they are very keen indeed on the European Communities Act 1972, the instrument that puts the Treaty of Rome in effect. They are mostly keen on the idea of repealing it – before the Lisbon treaty introduced an explicit procedure for exit from the EU, this was the closest anyone could think of to a procedure for departure.

Cameron, in my cynical view, is pushing this precisely because the final design of the bill might involve amending the 1972 Act, and so many of his party have been fantasising about this for years. Similarly, Dan Hannan has accidentally confirmed something I long suspected by quitting his job as legal spokesman for the Tories in the European Parliament in order to campaign for more referendums in general; it’s not any specific European treaty provision that excites him, it’s the idea of having a referendum he thinks he could perhaps win. It’s the mirror image of Der Tag, the day of the revolution.

It may be that the whole point of this was to flush out the crazies. Supposedly, old-fashioned drill sergeants would use various tricks to encourage the potential fainters to faint before the parade; in the same way, it’s better if people like Hannan and Roger Helmer to explode now and then have nothing left for when it matters.

But I’m still repelled by the idea of passing entirely pointless laws for intra-party political purposes.