The House of Commons voted overwhelmingly yesterday – by a margin of 554 to 53 – to support the EU Referendum Bill. Labour’s Damascene conversion to the belief that the people deserve a say, after years of opposing the very same principle, helped the Bill along.

But while the overall question of holding a referendum is no longer in doubt there remain a few wrinkles to be ironed out. Probably the most important is the Government’s attempt to scrap purdah – the period in the run-up to the vote during which the Government itself is forbidden from campaigning.

Purdah has been attacked before – during the 2004 North East Assembly referendum Ministers traipsed round in open breach of the rules begging people to vote Yes (they duly voted No). That was bad, but abolishing a long-standing rule of our democracy would be even worse. For Better Off Outers like myself, it raises the prospect of an unfair ballot. For advocates of staying in the EU, it should worry them that even if they won then their victory could immediately lose credibility thanks to a suspicion that such a measure had been used to deliver the “right” result.

Looking through the records of yesterday’s debate, the Government ought to be concerned about the source of criticism of the proposed abolition. There were the Tory eurosceptics, of course – that was to be expected. But there were other voices that should ring alarm bells. Dominic Grieve, who declared “I expect that I shall argue for a Yes vote in the referendum”, argued that the proposal was mistaken:

“…we have to be careful to provide a level playing field and make it clear that the Government will not abuse their position. For that reason, I hope that the Government will focus on this issue. The change that is being introduced to legislation that we previously said was deficient in this respect could convey an impression that the Government will come in and try to load the dice, and that must be avoided.”

Notably, in this age of narrow majority government, there was also criticism from the DUP and from the SDLP, Labour’s Northern Irish ally.

Let’s consider the possible outcome of a vote on an amendment to ditch the plan to scrap purdah. There is pro- and anti-EU concern about the topic on the Tory benches. There are Northern Irish MPs of both unionist and Irish nationalist leanings who also think the Government has got it wrong. The SNP oppose a referendum entirely, and are looking for opportunities to discomfort the Prime Minister, so they’re a maybe. If Labour were to choose to join the push then such an amendment might pass.

Why would the mostly Europhile Opposition do so? There are two possible reasons. First, they would undoubtedly like a chance to put the Government on the back foot, not least to distract from their own ongoing woes. Second, they might realise that, with the referendum likely to fall on the same day as local and possibly devolved elections, even a partial lifting of purdah could be used by Ministers to aid the wider Conservative campaign. Protecting purdah would serve their interests on both counts.

On the point of principle, the Government ought to abandon its attempt to scrap the purdah period for the EU referendum. Politically, there is a chance that if it does not do so by choice then it might be forced to.