Jeremy Corbyn has delighted us for long enough. When he was elected, as the accidental beneficiary of anti-Blairite feeling, to the Labour leadership, it was only fair to give him a polite hearing.

He success sprang, after all, from the deep dissatisfaction on the Left with the way the Labour Party has been run since 1983, and it was just conceivable that he would prove sufficiently eloquent and resourceful to express that anger in a way which resonated with the wider public.

He has now demonstrated his ability to do something rather different, namely to produce dismay and fury within his own party. The issue which has brought matters to a sudden head is how to respond to the attacks in Paris. Corbyn’s response could scarcely have been feebler. He denied this morning on the Andrew Marr Show that he is a pacifist, but he is certainly a prominent figure in the Stop the War Coalition, and many of his own MPs would be hard put to tell the difference between Corbyn and a pacifist.

The writer Robert Harris today expressed, in the Sunday Times (£), the impossibility of Corbyn as Labour leader:

“Far earlier than anticipated, the moral and political crisis that was always implicit in Corbyn’s election has arrived. Corbyn is, to all intents and purposes, a pacifist. But Labour has never been a pacifist party. It condemned the 1938 Munich agreement with Hitler and then joined the wartime coalition only on condition that Chamberlain stood down as prime minister. It helped found Nato. It developed the atom bomb. It fought the communists in Korea. It maintained and improved the British nuclear deterrent. After more than 75 years of active internationalism and willingness to use force, it is Corbyn who is the aberration.”

This matters because Britain now has to decide, in a Commons vote, whether to stand shoulder to shoulder with France, or to reject military action. There are, of course, arguments against taking action: but when Corbyn makes those arguments, he is is naturally suspected of yielding to his pacifist inclinations. He conveys the unmistakeable impression that if it was up to him, Britain would simply opt out of the fight against terrorism. So as Harris says,

“Let us hope…that enough Labour MPs have the courage to defy their leader and his virtual army and ensure that Britain plays its part in the UN coalition against ISIS. Because if the vote goes the other way it won’t only be the Labour Party that will have been revealed as supine, unreliable and irrelevant in the teeth of this crisis — it will be the entire country.”

While his fellow Socialist, President Francois Hollande, seeks to rise to the level of events, Corbyn evades and prevaricates. Unless Labour MPs can steel themselves to defy him, he will disgrace them, and diminish our country.