“I just wish Corbyn would duff up May.” So said a gloomy member of the press gallery as we trooped out of PMQs. For it strains invention to pretend that May duffing up Corbyn is unexpected.

Nor, one might add, is the sight of Corbyn duffing up Corbyn at all unusual. The self-indulgent habits he acquired in his decades as a maverick backbencher, including a refusal to get to grips with any subject or even entertain any thought he finds personally disagreeable, make him the least professional performer at Prime Minister’s Questions in living memory.

Before he could question May, she took the precaution, in response to one of her own backbenchers, of saying of the Windrush generation, “these people are British, they are part of us”. And she also reiterated her apology to any members of that generation who have wrongly had their right to live here as British citizens challenged by the Home Office.

Corbyn tried and failed to embarrass her about an individual case, who turned out not to belong to the Windrush generation, and then enquired about the destruction in 2010 of the Windrush landing cards.

May: “The decision to destroy the landing cards was taken in 2009 under a Labour Government.”

Triumphant Tory barracking of Corbyn, which the Speaker at length managed to quieten, after which the Leader of the Opposition demanded “absolute clarity on the matter of the destruction of the landing cards”.

His inability to take a point has become an embarrassment. So has his prolonged inability to reassure his own deeply distressed MPs that he takes the problem of anti-Semitism within the Labour Party seriously.

May praised the brave speeches made yesterday on that question by Labour backbenchers including Luciana Berger and Ruth Smeeth who have suffered vile anti-Semitic abuse.

And when Corbyn accused her of being callous, she retorted that she would not take that accusation from “a man who allows anti-Semitism to run riot”.

Oh dear. The Prime Minister’s greatest admirers would not pretend she is brilliant at thinking on her feet in the Commons. But compared to Corbyn, she is at least, for most of the time, professional.