When the 'make or break' summit to save the euro finished in Brussels on Friday afternoon, David Cameron headed rapidly for the exit without the traditional end of summit press conference (making do, unusually, with only an interim pre-dawn one as the leaders stumbled out from their almost ten hours overnight talks for a short break before breakfast).

As the dust settles from this critical summit, the gap between the UK and other European countries has never been wider, nor the UK's influence closer to zero. As Tory sceptics applaud what any sane observer would call a major foreign policy disaster, could it be that Cameron is in the process of taking the UK out of the EU without a referendum?

German leader Angela Merkel did give an end of summit press conference, answering questions, in a room overflowing with European and international journalists, about the outcomes of the summit, including the UK's marginalisation. 23 of the EU member states agreed at a marathon overnight session to sign up to a host of measures to contain the euro crisis through a new legal treaty committing to greater budgetary discipline including balanced budgets, quasi-automatic sanctions and a strong interventionist role for the European Commission. As Angela Merkel explained, only the UK - out of the four countries not immediately signing up - clearly distanced itself from this (while Sweden, the Czech Republic and Hungary will consult their parliaments before deciding).

But the UK did more than distance itself, it essentially used its veto to stop the other 23 member states revising the EU's treaties - something which needs all 27 members - even though the agreements on tighter fiscal coordination would not have applied to the UK.

Cameron, playing a weak hand, thought he could force concessions from Merkel, Sarkozy and others, and failed miserably. But covering his failure by forcing the other member states to agree a new treaty outside of the EU - which is what they have committed to do by March next year - is a spectacular own goal. The UK has been left with no allies in the EU and precious little good will - and while in some quarters there is irritation and antagonism, mostly the UK is now so marginalised it is seen simply as increasingly irrelevant.

With 23 member states - possibly all 26 - ready to sign a separate treaty, there will effectively be a parallel organisation, EU-23+ which the UK will have absolutely no influence on at all. It is no longer a question of two-speed Europe: it is the UK out on a limb, a large Norway, though with much less good will from other European countries than Norway can count on.

Predictably the eurosceptic press and backbenchers are overjoyed. But perhaps one positive outcome of the UK now having the weakest political influence, and most ineffective political strategy, of any point in time of its 38 years of EU membership, will be that we can now have a serious British debate about this.

In their 18 months in government, the coalition - LibDems too - have presided over a steady decline in the UK's influence and role in Europe, despite the UK being one of the biggest three member states by population and size of economy, and despite the euro crisis imperilling the UK too. As Merkel said we are all in the same boat. If the euro implodes, the UK will be as damaged as any other country by the economic and political shockwaves - but Cameron, and Clegg, have chosen to sit on the sidelines admonishing Merkel and Sarkozy.

The UK's diminishing role in the EU had been largely invisible in British politics and media until this summit. But now it is out there in capital letters. And despite the noisy tory backbenchers, the complicity of Nick Clegg and the invisibility of Ed Miliband, there are plenty of people in the UK who welcome being in the EU, able to travel, and work, and set up businesses, trade freely, influence EU foreign policy and climate change policies - who will not want the UK to be a small cut off island on the edge of the continent, with no influence in Europe let alone the wider world.

The Tory sceptics have been calling for a referendum. So the pro-Europeans should rise to this challenge. Cameron has taken the UK almost to the exit door of the EU with no debate and no consultation. A real public debate about the pros and cons of staying in the EU - including not stymieing the efforts of fellow member states in the midst of deep crisis - can perhaps rescue the UK from this foreign policy folly. Some will say who would vote for the EU in the midst of such a crisis. But if the euro survives - and today's summit shows the political will of the other 26 member states that it should survive - then the EU will rebound. So does the UK want to be a serious player in that EU or not? And if the euro collapses, the political as well as economic shockwaves will be huge - but the UK's behaviour at this summit and over the course of the crisis will ensure it is not an influential voice in trying to build cooperation out of the wreckage the failure of the euro would bring.

The big story for now remains the euro crisis. The UK is a sideshow in EU politics - it's time we decided if that is all we want to be.