Tories tend to think that Jeremy Corbyn as Labour leader will be fabulously useful for their party, returning them an even bigger majority in 2020 and pitching his own party into such turmoil that it struggles to work as an effective Opposition. But one benefit of his leadership to the existing Tory majority has been overlooked, which is the effect it would have on the Democratic Unionist Party.
Sources in the DUP point out to me that given Corbyn’s friendship with Sinn Fein, they would be unable to work with Labour to exert pressure on the Conservatives in key votes. This may mean that the eight DUP MPs are more likely to vote with the Conservatives, thus boosting their tiny majority of 12.
Of course, it may mean that the DUP continues to do its own thing but without any informal partnership with Labour, as it did in the last Parliament. But it will be much less amenable to doing anything that helps a Corbyn-led opposition out.