Jeremy Corbyn dug himself into such a deep hole that by the end of his speech only his head was visible. These ought to be great days for the Leader of the Opposition as he faces a Prime Minister whose party is deeply split on Brexit.

But by taking almost no interventions, and in particular by refusing to allow Angela Smith (Lab, Penistone and Stockbridge) to intervene, he instead managed to advertise the divisions within the Labour Party, and his own unfitness to take over as Prime Minister.

Can it be that Corbyn is a Tory agent? No. He is a man too weak, too full of a petulant and immature vanity, to brook contradiction from his own side, or indeed from any side.

Smith wants a second referendum. Corbyn ought to be able to cope with her. He instead reduced the House to pandemonium by insisting on holding the floor against just about everyone, though Michael Gove did manage to ask: “Why is he scared to take an intervention from the Member for Penistone and Stockbridge, a member of the Labour Party for 37 years?”

Corbyn just said that was a leadership bid by Gove. It was actually an expression of anger that Corbyn, of all people, whose career until he became leader consisted of saying whatever he wanted from the back benches, was now trying to crush debate.

And Theresa May did manage to ask whether Corbyn’s call for a Customs Union meant accepting the Common External Tariff, and various other aspects of the present Customs Union.

“Obviously, Mr Speaker, a Customs Union would be negotiated,” Corbyn said.

May, who spoke before him, was no more revealing on some aspects of her policy, and was indeed accused by Lady Hermon (Independent Unionist, North Down) of being “nebulous”.

But the Prime Minister was more animated than usual, as if she finds adversity stimulating and still thinks she sees a way through. She took plenty of interventions without losing her thread, and said she was listening to the House, and wanted to take to Brussels “the clearest possible message” about what it wants.

The Tory tribe gave signs of coming together. She said that getting legally binding changes to the Withdrawal Agreement will involve reopening it, “for which I know there is a limited appetite among our partners”.

Nigel Dodds, Commons leader of the DUP, rose at this point and assured her of his support. Nicky Morgan and Jacob Rees-Mogg made encouraging interventions.

Yet David Lidington, sitting beside her on the front bench, who in the past has managed to look perky even on the toughest days, today seemed despondent, as if he now sees no way through.

The Speaker had great difficulty maintaining order, and was gratuitously rude to a number of Conservatives. But the main fault for the bad behaviour lay with Corbyn, who was so determined to shut down debate while he spoke. His deficiencies remain one of the most cogent arguments for sticking with May.