Many have written that Jeremy Corbyn's likely election as Labour leader will give the Conservatives free rein to pursue their desired politics. But with a majority of just 12, their room for manoeuvre is more limited than suggested. In an Evening Standard column in July, I noted that Corbyn's success could deny David Cameron the Commons majority he needs to extend military action against Isis to Syria.

Speaking in Spain today, where he is discussing his EU renegotation, Cameron said that he would "only pursue going further on this issue if there is genuine consensus in the UK". That is a signal that military intervention would require bipartisan support. The Prime Minister is still stung by his defeat over the issue in 2013 - the first time a government had lost a vote on a matter of peace and war since 1782. Having previously opposed the extension of air strikes from Iraq to Syria, Harriet Harman said in July that Labour would look "very, very seriously" at any proposals to "tackle the growing horror of Isil".

But Corbyn, to put it mildly, does not share this view. Asked during last night's Sky News hustings by Liz Kendall whether there were any circumstances in which he would approve the use of armed force, he said: "Any? I am sure there are some. But I can’t think of them at the moment." He went to argue that interventions required UN backing to be legitimate: "We should have stuck with the UN and given far more support to the UN," he said in reference to the Nato action in Kosovo. "Surely we want to live in a world that is based on the rule of international law. the UN is quintessentially part of international law."

As well as the potential that a Corbyn leadership has to shift the terms of debate leftwards, forcing the Tories to adopt a more centrist position, this is another reason why not all Conservatives relish the prospect of his victory.