Gordon Brown will want to talk about anything but the EU reform treaty when he hosts Angela Merkel, the German Chancellor, at 10 Downing Street today. Europe is about the only issue where Mr Brown is on the defensive, in the face of demands for a referendum backed by four fifths of the public.

Unlike, say, the Irish Republic, Britain does not have explicit rules for when a referendum should be called. It has always been a question of political expediency, or rather prime ministerial weakness, as when Tony Blair in 2004 promised a referendum on the original constitution before its rejection by French and Dutch voters.

Mr Brown insists that the reform treaty is different from the constitution, even though other EU leaders and, most recently, the EU great and the good (the Amato group) have argued that the differences are largely symbolic. Ministerial claims that the reform treaty differs in form and character from the 2005 constitutional treaty sound like pedantic legalism.

However, Mr Brown is correct that the treaty as it affects Britain is not the same as for the rest of the EU, because of the exclusions (negotiated by Mr Blair): opt-ins on the charter of rights and on justice and home affairs, protecting UK law; keeping an inter-governmental approach on security and foreign and defence policy; and control over taxation and social security.

The underlying question is whether the proposed changes (less than in the 2005 treaty) justify a referendum. Of course, some ultra-sceptic groups would allege that a superstate was being created whatever was proposed. The latest absurdity is the claim that Britain will lose its seat on the United Nations Security Council. That is utterly wrong. The draft restates the existing position, whereby an EU representative can speak but only when member states with a seat on the council request it on a policy where there is consensus.

But Mr Brown will not defuse the demands for a referendum, which have a wide appeal. The question is, whether this will matter electorally. The sceptics have made much of a new ICM poll showing that 24 per cent of Labour voters say they would be less likely to vote for the party if it opposes a referendum, with 13 per cent saying it could increase their likelihood of voting Tory if the Conservatives promised a ballot. But as Anthony Wells, of UK Polling Report, says: “Telling a pollster you might not vote for a party if they don’t do something you want is an easy hit. It’s not the same as actually doing it.”

A majority of the British public oppose the treaty. But, apart from a vocal minority, voters do not care that much about Europe as opposed to health, crime and jobs. And past evidence shows that the more the Tories talk about Europe, the more they damage their own chances. Arguments about the EU would complicate an autumn election, not least because the treaty talks are due to be concluded at a heads of government summit in Lisbon on October 18. But whatever the sound and fury of the sceptic press, Mr Brown can probably ride out this issue. The EU will not decide the next election.

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