Editorial: Jeremy Corbyn was a disastrous leader for Labour yet it is dysfunctional for the party to bar him from even being a candidate for them

​In the 2017 general election, Jeremy Corbyn led the Labour Party almost to victory.

He won 40% of the vote, a mere 2% behind the then prime minister Theresa May, who had been expected to cruise to re-election.

Mr Corbyn's share was higher than most other Labour results since World War Two, and was close to the vote levels achieved by Tony Blair in his 1997 landslide. The success that year of Mr Corbyn, a veteran leftist, shook the political establishment, and cast doubt on the conventional wisdom that Labour had been mad to adopt such a leader.

To be clear, this newspaper thinks that Mr Corbyn was always going to be the disastrous Labour leader that he proved to be. He would have been a disastrous prime minister. On almost every major issue of the day over the decades he has been wrong, from membership of Nato to the right of police to use lethal force to stop Islamist mass murderers. It is a sign of his atrocious judgement that, like his shadow chancellor John McDonnell, he seemed sympathetic to IRA terrorists. He certainly declined opportunities to condemn unequivocally their violence.

Yet Labour has every right to choose the leader it wants to choose. It chose Mr Corbyn and, to everyone's surprise, that choice resonated with a large swathe of the UK population.

Now Mr Corbyn, after 40 years of being a thorn in the side of the mainstream Labour establishment but nonetheless a dedicated servant of his party, has been barred from standing as an MP for it in his Islington constituency. We defend the right of Labour to have its own rules on candidates. But it is both dysfunctional and utterly lacking in credibility to have someone as your leader, and to have top Labour politicians such as Keir Starmer to serve under him in one election and then, in the next, stop him even becoming an MP.