BUOYED up by Liberal Democrat successes in last week's local council elections, my return to Brussels has plunged me into the decisive phase of the work of the European Convention, drafting the new constitution of the European Union.

BUOYED up by Liberal Democrat successes in last week's local council elections, my return to Brussels has plunged me into the decisive phase of the work of the European Convention, drafting the new constitution of the European Union.

The average Briton could be forgiven for knowing nothing at all about the Convention. The heavier broadsheet newspapers carry a story when there's a row brewing. The BBC, the state broadcasting company, has no resident journalist in Brussels covering EU affairs generally, let alone the Convention in particular. At Westminster, the government tries to mislead the House of Commons into believing that the Convention is a merely tinkering sideshow.

Prepare yourselves – the European Union will have a written constitution before the UK. The powers of the Union, its values, goals, institutions and decision-making procedures will soon be entrenched in a document that will be very hard to change thereafter.

The constitution, which will be agreed by this time next year, will mark a new and more ambitious stage in the unification of Europe. In particular, it will empower the EU to act effectively on the world stage. In view of this year's profound European disunity over how to handle the United States of America, this prediction may seem startling. But the Iraq crisis has stimulated much-needed fresh thinking in the Convention about a common foreign, security and defence policy.

Radical changes are being proposed to the existing feeble system, which would allow a coalition of politically willing and militarily capable member states to go forward alone to act like the motor of integration.

The big question that nobody knows the answer to is: what will Britain do. The Tories, we know, will oppose the new constitution. We Lib Dems will support it. The Labour government's performance in the Convention has been poor and its objectives unclear. Now more marginalised in Europe than ever as a result of the Iraq War, the UK faces a critical turning point in its European relations. If Mr Blair chooses to reject the constitution, he would at least be being consistent with past UK government policy.

Britain's historic role in Europe has been to dilute the drive to European unity and, when the going gets tough, to cling to Washington. Successive governments have failed to speak the truth to the British public about the true scale and purpose of European Union.

We are as a nation ill-prepared for the further transfer of sovereignty to the EU that the Convention and its constitution implies. But our consent is required for the transformation to happen. That decision, and that of the euro, present Mr Blair with the biggest test of his premiership.

Andrew Duff is the Liberal Democrat Member of the European Parliament for the East of England. www.andrewduffmep.org