When we ask Parliament to debate whether the ‘advice’ of the advisory referendum should be taken, and when we ask Parliament to debate whether or not to trigger Article 50 of the Lisbon Treaty, we are asking for the same thing.

In asking for a debate and a vote on this matter, we are asking Parliament to exercise its sovereignty. MPs were told in Briefing Paper 07212 on 3 June 2015, before debating the European Referendum Bill, that the referendum was only advisory and consultative and therefore non-binding (section 5); and they were alerted to the fact that if there were any question of the referendum being other than merely consultative and non-binding, that ‘a simple plurality of votes’ (that is, an ordinary majority) would not be enough (section 6). Yet on the evidence of what the Government and a number of MPs say, when they claim that they take the referendum result to ‘mandate’ Brexit, you would think that they had not read the Briefing Paper.

If they did not read it, their failure to do so is a serious dereliction of their duty as MPs concerning so serious a matter. If they did read it, the possible explanation for their acting as if they did not read it, is that they did not understand it. Which is it?

In the debate thus being asked for, we have every right to expect MPs to vote according to their pre-referendum position on membership of the EU. They were elected to Parliament in part on the basis of that position, and reneging on it now must raise questions in their constituents’ minds. It is a relatively easy matter not just to identify on which side of the debate MPs stood before the referendum, but also to recover their words explaining the damage Brexit would do, and the many advantages of EU membership. How can they have changed their minds so suddenly and dramatically as not to see that they have a powerful opportunity to keep the UK in the EU where they believe it belongs?

Would they now say, along with the monstrously disingenuous Mr Boris Johnson, that their arguments in favour of continued EU membership were merely ‘parodic’? In the case of all three major political parties, continued EU membership was official party policy. Is all their support for party policy merely ‘parodic’?

The only thing that is completely and unequivocally clear in the current situation is that Parliament must debate and vote on whether the ‘advice’ of the advisory referendum should be taken, or (same thing) whether or not to trigger Article 50 of the Lisbon Treaty. And when they do, Party Whips should not be involved. The vote should be a free vote. There has even been a suggestion that it should be a secret vote, to spare the anxieties of timid MPs who might not vote as their own informed judgment prompts them, for fear of losing their jobs – although as representatives not delegates, with a responsibility to give leadership and to make the case for their decisions, they should be prepared to act on principle, not out of pusillanimity.

The question before us all is whether we want the UK to be a major leading nation in one of the three big blocs of influence in our world – USA, China, EU – or whether we want the UK to become an isolated offshore entity of diminished and diminishing significance in the world. The economy, and the opportunity to influence world affairs which will impact upon us whether we like it or not, is at stake. We can be poorer and without influence outside the EU, or we can continue to be one of the leading economies and one of the leading players in the world as a major part of the EU.

A small isolated UK will not merit its seat on the UN Security Council. A small isolated UK will soon not be a member of the G7 largest economies in the world.

Indeed when one thinks of the shrinking of the UK, it even occurs that the English language will falter as a world language: Mandarin and Spanish are the world’s big languages in population terms; the US is already 50/50 Spanish and English; if the UK leaves the EU, the dominant languages in it will be French and German. Wither English then? It might take a generation, but our own grandchildren will look back and wonder at the act of national suicide which led a once-great country into the shadows of marginalisation.

From both personal knowledge of people who have indicated this, and from observation of the same thing being said in the social media sphere, I see scientists, business owners, Europhiles and others saying that they contemplate leaving a Brexited UK in order to swim in the far larger sea of possibilities that the EU and US offer in comparison to what an isolated offshore Brexited UK (or what is left of it) can offer. A brain drain, a drain of creative talent and high-achieving entrepreneurship, of the kind that happened elsewhere in the 1930s, would accelerate the decline of the UK yet further.

Brexit, as all this shows, is an existential risk to our country.

There might actually be some politicians and other individuals who do not care about any of this, and who want to leave the EU at any price. Perhaps they do not feel up to playing with the big kids in the playground. They might prefer – to vary the metaphor – to be big frogs in a small pond, no matter how small – even if the UK breaks apart as a result. When I hear Little Englander politicians like John Redwood I think this might be so.

But then I think of our history: of how our country played such a major role in world affairs, but always in concert with others – with (successively) an empire, a commonwealth, allies, partners. I think of how well the UK has done since the Treaty of Maastricht in 1992 which Mrs Thatcher signed. The lesson is crystal clear: we are better, stronger, far more influential, in than out of the EU.

Parliament has the chance to keep the UK in the EU and on track. The EU is imperfect; it is a work in progress. In it we can help it evolve and improve. Whether we are in or out of it, it will be a huge influence over us. If we are out of it and it evolves in ways which are even less to our taste, and less comfortable in its influence on us, we will rue Brexit even more. Obviously, being inside and able to shape that influence is immensely better than being outside and helpless in the face of it.

Membership of the EU is a no-brainer: economically, in terms of peace, progress and prosperity, in co-operation with our fellow Europeans, as a leading part of a major world bloc, as partners in a grand project. Should Parliament take the ‘advice’ of the advisory referendum? Should it (same thing) debate whether or not to trigger Article 50? The answer to that is a no-brainer too.

Professor A C Grayling 
Master, New College of the Humanities