Much is being said about British opt-outs from the revived EU constitutional treaty, but without making it clear that an opt-out is never seen as a permanent exemption.

On the contrary, in view of the over-riding principle of "ever closer union" it is presumed that the most integrationist provisions included in any EU treaty must eventually apply to every member state, without exceptions.

Moreover the decision to partially or completely relinquish a British opt-out rests with the party to the treaty, the British government.

A government may use opt-outs as a temporary expedient to avoid holding a referendum on a treaty. Later the same or another government may decide to abandon those opt-outs, also without any referendum.

No opt-out can ever be regarded as safe. In a recent interview Gordon Brown confirmed that in principle he is still in favour of joining the euro, dropping the opt-out obtained by John Major to help get the Maastricht Treaty through Parliament.

If we let Labour MPs get away with openly breaking their manifesto promise to hold a referendum on the EU constitutional treaty, why should they feel any need to keep their equivalent promise about holding a referendum on whether we should scrap the pound and join the euro?

MURIEL PARSONS, Berkshire chairman, Campaign for an Independent Britain.