Corbyn's leadership crumbles in a humiliating fashion

This is not merely because he is radical.

Mr Corbyn can (of course) be as radical as he wants to be and the Labour Party can (also of course) choose as radical a leader as it wants to choose.

The problem is that the party’s MPs and supporters did not want a radical leader but the voters in the last leadership election did want it. There are a number of reasons for this, including the fact that membership, and thus voting rights in that contest, was made so cheap and easy.

But also the membership has ended up being far removed from the average Labour voter, almost 40% of whom backed Brexit (and for reasons such as immigration, not for the traditional leftist reasons that Mr Corbyn always opposed the EU).
The referendum showed how ill-suited a man such as Mr Corbyn is to leadership of a mainstream party. He was not able to campaign for a hardcore socialist critique of the EU.

Mr Corbyn was widely admired as a principled backbencher before he became leader. Now he is widely mocked.

He has seemed weak, partly because he is not able to express what he really feels, and partly because his mild temperament lacks the authority needed for leadership. For months, he has experienced one embarrassment after another, culminating in these unprecedented mass resignations.

There are lessons for all parties in this: they pride themselves on being so democratic and then often do not like the decisions that their members take. It has happened in the Republican Party in America, where Donald Trump triumphed despite being bitterly opposed by the party’s high command, and it may yet happen in the Tories, where Boris Johnson is more popular with the grassroots than with fellow MPs.

It has been painful to watch Mr Corbyn’s progress. If he is somehow ousted, and stands again as leader, and wins, the Labour Party will almost certainly splinter. It will certainly lose a general election. Having an unelectable opposition is good for the Conservatives, but it is not good for democracy.