In a life-enhancing essay that confirms, if nothing else, that he would have been the all-time ideal dinner party guest, Robert Louis Stevenson writes that to talk with others about the affairs of the day is to “bear our part in that great international congress, always sitting, where public wrongs are first declared, public errors first corrected, and the course of public opinion shaped, day by day, a little nearer to the right”. The written word, to which Stevenson himself brought such a gifted hand, will always fall short of the richness of the talk that precedes it, he argues. Literature itself “is no other than the shadow of good talk” in which “the imitation falls far short of the original in life, freedom and effect”. Indeed, no legislative measure ever comes before parliament, Stevenson suggests, unless “it has been long ago prepared by the grand jury of the talkers”. Modern Britain should honour the good sense of this grand jury of talkers more attentively than it does. Disturbingly, this is not a view to which everyone now subscribes. Brexiters such as Nigel Farage, David Frost or the Daily Mail certainly do not. For them, to even mention Brexit in any terms other than a dragooned and uncritical celebration of Britain’s departure from the EU is anathema and dangerous. In their near-hysterical responses to news that a group of all-party politicians and assorted experts had met to discuss how Brexit could “work better with our neighbours in Europe” last week, the critics went straight to ramming speed. The meeting at Ditchley Park in Oxfordshire was variously condemned as a “full sell-out” (Farage), a “plot” (Frost) and “a smug assemblage of arrogant establishment figures who think they know best” (a Mail editorial). In reality, there is no evidence that last week’s meeting was any of these things. Ditchley Park conferences are not secret summits. They are off-the-record conversations attended by senior politicians, officials, academics, business figures and – yes – journalists. There are normally 30 or more people around the table. Full disclosure: I have been to Ditchley events too, though not last week’s, more’s the pity. There is a list of the kind of things they discuss on the Ditchley Foundation’s website. It is a wide-ranging agenda. There is a conference next week on AI. In March, there is one on Germany’s new direction. Yes, the Ditchley director tends to be a retired Foreign Office grandee. Yes, they are select gatherings, possibly too much so. And no, their contents are not reported. But perhaps, as Stevenson puts it in his essay, “the profit is in the exercise, and above all in the experience; for when we reason at large on any subject, we review our state and history in life”. All of that said, the Brexit event, which two journalists attended, appears to have been unusually carefully choreographed, even for Ditchley. Yet given Ditchley’s role and purpose, surely it had to be so, as the overreactions have confirmed. It was essential that this was not, contrary to Frost’s claims, a remainer event, and essential that non-isolationist leavers would agree to take part in it. That is why it was important that leavers such as Michael Gove, Michael Howard, Norman Lamont and Gisela Stuart attended, along with Alex Hickman, who served as Boris Johnson’s business adviser between 2020 and last summer. It was significant that they came. But it was equally important that remainers including David Lammy, John Healey and Peter Mandelson came from the Labour side, along with the Tory remainers Jonathan Hill and David Lidington, and former officials including Olly Robbins and Tom Scholar, who was fired from the Treasury last autumn. No current officials were invited. They all went to the event, from their different starting points, because they all grasp that there is an issue worth solving that cannot be wished away, blamed on betrayal by Brexit fainthearts, or concealed by airy talk about Brexit freedoms. The negative impact of Brexit on the UK economy in 2023 is not a matter of opinion but of fact, as analysis from the Office for Budget Responsibility makes clear. That fact confronts Rishi Sunak’s government today. That is why Sunak is so keen to get a reformed Northern Ireland protocol over the line, while characteristically flinching from telling his party the truth about Brexit. But the same fact would still confront a Keir Starmer government in the future, too. The economic cost was underscored this week by the comments from Jonathan Haskel, a member of the Bank of England’s rates setting committee, that Brexit has wiped out £29bn in business investment and exacerbated the UK’s productivity slowdown. It is already responsible for a 1.3% loss of GDP – a loss of £1,000 a household – and will more than double to 2.8% of GDP by 2026. On Tuesday, the work and pensions secretary Mel Stride agreed as much. There is a much larger point here, too. British politics has a void where a public conversation should be between people with opposing views on Brexit. That conversation has to focus on the economic facts and political options as they actually exist, rather than as the protagonists from 2016 might want them to be. It is not an easy conversation, but it is beginning to take place all the same. Overwhelmingly the most sensible response to the revelation about the Ditchley discussion should be to say, “About time, too”. This meeting was not an outrage. The participants are not, as some leavers want them to be, a latterday Cliveden set of influential aristocrats. For this was a meeting that ought to have taken place a long time ago. UK governance has been and still is immobilised over Brexit. For anyone who believes in trying to solve problems, the mature response to such a meeting is: “Good. Now, what’s the next step?” It needs making clear that neither the conversation that we need, nor the conversation that I assume took place at Ditchley, is about re-running 2016. There are more layers of meaning bound up in the Brexit referendum than merely a profit-and-loss calculation, important though that is too. It is striking that the leavers at the meeting were clear that there is an economic problem that justified their attendance, even though they do not believe this invalidates the UK’s separation from the EU. Several of those whom I approached for comment on the Ditchley meeting were irritated that the news had come out. They are wrong to take this view. Stevenson’s grand jury of talkers has been on the case for ages. It was time that political leaders caught up and opened up, and time they confronted the true believers. Yet Brexit is a problem that the current government is incapable of solving. Conservative divisions remain too fundamental, as the upcoming confrontations over reform of the Northern Ireland protocol are likely to show, perhaps very damagingly. Sunak knows that Brexit is a problem, not a liberation, but he cannot say so. In the end, though, it is action that will be needed, not talk. Martin Kettle is a Guardian columnist