There is a paradox in our relationship to Europe. While successfully putting Britain in a far more influential position in the EU than our critics give credit for, Labour has failed to confront the visceral anti-Europeanism in British political culture. In retrospect, the long debate about British membership of the euro divided Britain's progressive pro-European constituency. For the "pros", which I remain, there was never a knockdown argument as to why Britain had to take the bold and uncertain leap of joining. Until the recent German recovery, the poor performance of the eurozone cast a pall over the debate. But with UK membership of the single currency on ice, the realities of globalisation are shifting the debate on to more favourable ground for pro-Europeans because of the lack of national solutions to its challenges.
The same principle is true in dealing with the economic superpowers of Asia, or for our armed forces to share more and do more together under European defence. How, post Iraq, can we establish a more equal relationship with the US except by putting more effort into building common European positions, as we have done on Iran?
But globalisation is not just about using the EU as a multiplier of diminished national power. It also forces us to decide what our values are and who we share them with. Britain is approaching the levels of public spending of a European social democracy - which the Cameron Conservatives are claiming they will not fundamentally reverse. At the same time, following enlargement, the rest of the EU has become more "British" in its attitudes towards market reforms.
In October 2005, an under-reported event took place at Hampton Court during Britain's EU presidency. Among other things, the Hampton Court summit put the urgent issue of climate security and Europe's pressing energy demands at the top of the EU agenda, culminating in the strategic set of policies unveiled by the European commission last week.
This experience demonstrates three things: the relevance of the EU to the 21st century's global agenda; the constant need for member states to supply strategic political direction to EU affairs; the indispensability of the European commission in converting strategy into policy - and sticking to it. Another lesson is for Labour itself to ponder as it debates its future: without an effective and accountable EU, with Britain at its heart, the party's capacity to fulfil its progressive ambitions will be severely diminished.
In Britain, progressives should be more vocal about what New Labour has achieved and about the scale of the challenges we still face, along with our European partners. To recognise these commonalities is not to argue for centralised action from Brussels. We ought to recognise that, as modern social democrats, we are Europeans with shared values. It is time for the progressive left in Britain to develop a stronger case for Europe.
A new push for Europe should focus on the need for collective, progressive policy responses, before engaging in a technocratic debate about Europe's institutions. It is important to judge the need for institutional change not for its own sake, but on the basis of what changes are necessary to strengthen Europe's capacity to act in meeting shared globalisation challenges.
Pro-Europeans need to rally a broad swath of British civil society for a more constructive approach to Europe. Britain's future lies within an EU ready to embrace a progressive agenda. Sidelining ourselves from the European agenda, or isolating ourselves from our European friends, would be disastrous. We must have the confidence to make a pro-Europe, pro reform-in-Europe stance a key battleground at the next election.
Peter Mandelson, the EU's trade commissioner.