Whose side is Jeremy Corbyn on? For whenever Theresa May is under pressure, he makes life easier for her by failing to look like a Prime Minister in waiting.

To watch him in action is to wonder what is the opposite of “forensic cross-examination”. Corbyn is pitifully weak at sustaining an attack which runs through six questions.

By the time he had finished, visitors to the House of Commons who had at first gazed down with rapt excitement from the galleries found it impossible to repress enormous yawns.

The Prime Minister patronised the Leader of the Opposition. At one point she said it was “a little difficult to detect the question”, at another that “perhaps he should listen to the answers”.

Remarks such as “nothing is agreed until everything is agreed” and “we are very clear that we will not give a running commentary” were quite sufficient to fob off Corbyn.

Her difficulty in finding a way forward which will satisfy both Jacob Rees-Mogg and Dominic Grieve remained entirely unexplored by the Labour leader.

The Prime Minister instead mocked the Opposition for being divided: “The only hard border around is right down the middle of the Labour Party.”

But hard things were said about her by her own Eurosceptics. Rees-Mogg asked her, before returning to Brussels, to apply “a new coat of paint to her red lines, because I fear on Monday they were starting to look a little bit pink”.

Bernard Jenkin pointed out that free-trade deals are not going to come our way “if we remain shackled to EU regulations”, while Peter Bone offered to strengthen her hand by coming over to Brussels with her.

She rejected that nightmarish prospect. But one day she is going to have to come back from Brussels with a deal which she can persuade Rees-Mogg, Jenkin and Bone to support.

Rees-Mogg, Jenkin and Bone sounds like a firm of provincial solicitors in which none of the partners is receptive to the suave metropolitan ambiguities that are all too likely to emerge from the talks in Brussels.

So this PMQs served as a useful reminder that May’s problem is not just with the DUP. It is with her own party.