The Staggers 8 February 2016 On Brexit, David Cameron knows exactly what he's doing It's not a dead cat - it's about disarming the Leave campaign. Photo: Getty Sign UpGet the New Statesman's Morning Call email. Sign-up If you’re explaining, you’re losing. That’s the calculation behind David Cameron’s latest entry into the In-Out (or Remain-Leave in new money) battle. The Prime Minister has warned that were Britain to leave the European Union, the migrant camp at Calais – popularly known as “the Jungle” – could move to Britain. But Eurosceptic campaigners have angrily denounced the remarks, saying that there’s little chance of it happening either way. Who’s right? My colleague Henry Zeffman has written a handy explainer of the ins and outs of the row, but the short version is: the Eurosceptic campaigners are broadly right. But the remarks are very far from a gaffe by Downing Street or Cameron, and they aren’t a “dead cat” strategy – where you say something offensive, prompting a debate about that instead of another, trickier issue – either. Campaigners for Remain have long been aware that immigration remains their glass jaw. The line wheeled out by Cameron has been long-planned. Late last year, senior members of the In campaign discussed what they saw as the danger points for the campaign. The first was a renegotiation that managed to roll back workplace rights, imperilling the support of the Labour party and the trade unions was one – happily avoided by Cameron’s piecemeal deal. That the deal would be raked over in the press is not considered a risk point. Stronger In has long known that its path to victory does not run through a sympathetic media. The expectation has long been that even substantial concessions would doubtless have been denounced by the Mail, Telegraph and Sun – and no-one seriously expected that Cameron would emerge with a transformative deal. Since well before the general election, the Prime Minister has been gradually scaling back his demands. The aim has always been to secure as many concessions as possible in order to get an In vote – but Downing Street’s focus has always been on the “as possible” part rather than the “securing concessions” bit. Today’s row isn’t about deflecting attention from a less-than-stellar deal, but about defanging another “risk point” for the In campaign: border control. Campaign strategists believe they can throw the issue into neutral by casting doubt on Leave’s ability to control borders any better. One top aide said: “Our line is this: if we vote to leave, the border moves from Calais to Dover, it’s that simple.” They are also keen to make more of the fact that Norway has equally high levels of migration from the European Union as the United Kingdom. While In will never “own” the issue of immigration, they believe they can make the battle sufficiently murky that voters will turn to the areas that favour a Remain vote – national security, economic stability, and keeping people in their jobs. What the row exposes, rather than a Prime Minister under pressure is a politician who knows exactly what he’s doing – and just how vulnerable the lack of a serious heavyweight at the top makes the Leave campaign(s). Most people won't make a judgement based on reading up the minutinae of European treaties, but on a "sniff test" of which side they think is more trustworthy. It's not a fight about the facts - it's a fight about who is more trusted by the public: David Cameron, or Iain Duncan Smith, Chris Grayling or Priti Patel? As one minister said to me: "I like Priti, but the idea that she can go against the PM as far as voters are concerned is ridiculous. Most people haven't heard of her." Leave finds itself in a position uncomfortably like that of Labour in the run-up to the election: with Cameron able to paint himself as the only option guaranteeing stability, against a chaotic and muddled alternative. Without a politician, a business figure or even a prominent celebrity who can provide credibility on the level of the Prime Minister, any row about whether or not Brexit increases the chances of more migrants on Britain’s doorsteps helps Remain – and Cameron. › Why Twitter is dying, in ten tweets Stephen Bush is political editor of the New Statesman. His daily briefing, Morning Call, provides a quick and essential guide to domestic and global politics. Subscribe For more great writing from our award-winning journalists subscribe for just £1 per month!