It is now nearly four decades since the British public voted to join the European common market.  The organisation has changed beyond all recognition since then without any further reference to the people.  The last Government promised a referendum on the constitutional treaty - and reneged.

The European Union is evolving further in its attempts to deal with the ongoing euro crisis.  As I argued when I set up the national 'no' campaign against joining the euro, no currency union has ever survived without political and fiscal union, and that is what the Eurozone's leaders are now seeking to forge.

Europe is our largest export market and it is in our national interest that its economies grow again.  But the new arrangements could affect us profoundly even though we are not in the Eurozone.

So we must protect our national interest, and we also have an opportunity to bring back powers from Brussels, something I have consistently advocated.  The Foreign Secretary has begun an audit of which powers could be returned, and this will report in the autumn.

My longstanding belief remains that we need fundamental reform of the European Union and our relationship with it.  I think it is right that the British public is given a say, and the Prime Minister has indicated that he thinks this, too.

As I said in a recent interview with The Times, the referendum question is not just an issue about our relationship with the EU.  It has become an issue of trust.  It is dangerous to have the perception of a political class who promise the public a say yet never allow it.

I have never advocated outright withdrawal.  Most Britons agree that we should be part of a sensible economic arrangement but not subsumed within a superstate.  But that depends on whether such an arrangement can be reached.

In my view, it is no longer a question of 'if' there will be a referendum, but 'when' and what the question will be.  The situation in Europe is evolving rapidly and we do not yet know what steps will be taken to preserve the euro, so we should not act precipitately.  But I do not believe we will have to wait much longer before the public rightfully have their say.

Christopher N Howarth