Amid the greatest political upheaval in its postwar history, Britain lacks an opposition. Jeremy Corbyn was elected Labour leader by a huge vote among the party membership in September. Since then he has shown himself devoid of leadership qualities and out of step with his MPs’ views. His parliamentary colleagues have watched in anguish as he fumbles set-piece occasions, floats half-baked ideas and alienates voters in Labour’s heartlands. Yesterday discontent boiled over as 11 members of the shadow cabinet departed.

The revolt is belated. Britain urgently requires a functioning opposition that offers a viable alternative government. Labour MPs have a moral obligation to provide it. They should cease to give cover to an incompetent bungler. If Mr Corbyn will not go voluntarily, the parliamentary party