Jeremy Corbyn managed to bring a smile to the wintry features of his press man, Seumas Milne, who watches PMQs from a bench on the right-hand side of the press gallery.

Corbyn achieved this rare feat by quoting David Davis’s assurance that Britain will not plunge, because of Brexit, into a Mad Max-style dystopia, and by asking: “Doesn’t the Prime Minister feel he could set the bar just a little bit higher?”

It was an excellent first line, which amused others besides Milne, who may himself have urged Corbyn to use it.

In private, when they are not subject to the scrutiny of the lackeys of the capitalist press, it is possible that the two men are as merry as Marx and Engels, and  regularly reduce each other to fits of laughter.

But in public, Milne wears the manner of a sea-green incorruptible: a man of revolutionary purity, who wastes no sympathy on the contemptible specimens of fallen humanity which surround him.

So it was good to see him smile for once. But Corbyn could not keep it up. He had chosen the right subject – Brexit – but was foiled by the Prime Minister’s bland assurances.

It is possible we have given too little credit to Theresa May for her defensive abilities, honed during her long stint as Home Secretary.

She adopts some smooth and unilluminating formula, which gives no purchase to the attacker, and sticks to it through thick and thin.

So when Corbyn asked what outcome the Government wants from Brexit, she replied that it is going to get “a bespoke economic partnership”.

She made the whole thing sound as simple as a shopping trip on which one orders a bespoke suit. The tailor takes your measurements, carries out a fitting or two, and there a short time later is the garment.

Perhaps on some future occasion Corbyn will point out that Brexit is a bit more complicated than ordering a suit. Instead he complained that “all we’ve had is waffle and empty rhetoric”, and asserted that the Government “isn’t on the road to Brexit – it’s on the road to nowhere”.

One could not help reflecting that once Brexit has happened, Corbyn could be find himself on the road to nowhere.

He had not given May the opening she wanted to use her joke, but she told it anyhow: “normally he stands up every week and asks me to sign a blank cheque, and I know he likes Czechs, but really…”

The rest of her words were lost in roars of laughter. For treating Corbyn’s links to a Czech spy as absurd was somehow exactly right.

After this sally, May became once more impenetrably dull. Milne gave a great yawn, and one could not blame him, for yet again the Prime Minister had bored her way to victory.