JEREMY CORBYN opened his overdue anti-Brexit speech this morning by observing that the venue, Senate House in London, was the inspiration for the Ministry of Truth in Orwell’s 1984. The comment—playfully questioning the sincerity of the arguments to follow—will have unsettled the pro-Europeans who dominate his Labour Party. For Mr Corbyn seems only recently to have converted to the case for British EU membership.As a paid-up member of his party’s old left-Eurosceptic wing who campaigned for Britain to leave the club at the last referendum, in 1975, he has a series of stringent criticisms of Brussels to his name. The union, he claimed in the past, is “directly responsible” for “gross abuse of human rights and natural resources” and its project “has always been to create a huge free-market Europe.” As recently as last summer Owen Jones, one of Mr Corbyn’s media outriders who was incensed by the Greek crisis, published an article floating the case for Brexit on left-wing terms, or “Lexit”. In one interview early in his leadership the man himself declined to rule out such a stance.This morning he extensively rehearsed his grumbles about the EU (“from its lack of democratic accountability to the institutional pressure to deregulate or privatise public services”) and made it clear that he will not be sharing a platform with David Cameron (who may struggle to endorse what the Labour leader called the “socialist case” for staying put). But he also marshalled the left-of-centre arguments for membership well enough, citing climate change, human rights and social protections and concluding: “you cannot build a better world unless you engage with the world.” Brexit, he observed, would happen not on left-wing terms but on those of Boris Johnson and Nigel Farage: “just imagine what [the right] would do to workers’ rights here in Britain if we voted to leave the EU in June.” Better, he argued, to stay in the EU and try and change it.This intervention should have two positive effects. The first is that by declaring the Labour Party “overwhelmingly” for membership, Mr Corbyn has licensed his front bench, MPs, counsellors and activists to throw themselves into the campaign. The second is that it sets out a template for the sorts of arguments needed to mobilise the leftish, younger voters who should be the backbone of the pro-EU vote but—with the official campaign period beginning tomorrow—have been looking worryingly apathetic.Did he mean it? Some, especially in the pro-Brexit camp, have suggested that Mr Corbyn was suppressing his Euroscepticism to avoid inflaming his already-fraught relationship with his party’s centrist mainstream. That is conceivable. As I observe in my latest column, the past months have seen those in his office who think he should pick his battles, like Seamus Milne, his strategy chief, win out over those who would prefer total war against the Europhile moderates.But this morning Mr Corbyn gave the impression, especially in the Q&A session after his speech, of having been genuinely persuaded of the case for membership. The fact that most prominent Brexiteers are on the right and push a free-market, anti-migrant sort of Euroscepticism must have helped put him off backing Leave. Another reported factor is the chance Mr Corbyn has had to get to know other European politicians since becoming leader: “Jeremy has discovered he quite likes meeting other leaders,” ran a quote in the Times yesterday. Most influential, perhaps, was the anti-Brexit urging of southern European leftists. Yanis Varoufakis, the former Greek finance minister who is informally advising Labour’s leader, recently told me that he had been encouraging Labour’s leader to endorse Remain (Mr Corbyn’s talk of remaining in the EU and reforming it from within bears the traces of his arguments). Antonio Costa, Portugal’s socialist prime minister, also cautioned him against “Lexit”—his case even receiving a mention in the speech.In this respect, and though he may not like to admit it, Mr Corbyn is not so different from some of his Conservative counterparts. Many are the British Eurosceptics whose doubts about the EU have mellowed, or at least been nuanced, by the experience of frontline political responsibility and of meeting and working with their European counterparts. That is true of David Cameron, whose appreciation and sensitivity for continental co-operation grew during his recent “renegotiation” of Britain’s membership. Likewise George Osborne, whose suspicion of the EU when he became chancellor in 2010 has, according to allies, evolved into a more tolerant position over the course of his stewardship of Britain’s economic interests. And having spent much of his career in Westminster bashing Brussels, William Hague attracted Eurosceptic accusations that he had “gone native” during his four years at the (institutionally Europhile) Foreign Office. (The exception is Michael Gove, who left the Department for Education more anti-EU than when he joined.)That general trend should give Britons contemplating a vote for Leave pause. Perhaps, as the anti-EU camp insinuates, political expediency and too much time munching canapés and hobnobbing with the Euro-elites drives it. But perhaps, just perhaps, those at the top of politics who have seen Europe close up and grappled with the responsibility for Britain’s future have peered into the abyss and seen that the leap is not worth the risk. Familiarity with the EU may not breed “content”, but it does seem to push British leaders towards the conclusion that continued membership is in the country’s interests, malgré tout.