At 11.58 there were cries of “Hear, hear” from the Tory benches as Theresa May, looking a little pale, entered the Chamber. Seema Kennedy, her Parliamentary Private Secretary, who sits on the bench behind her, looked a little pale too. It’s been a stressful time.

Cabinet Office Questions meandered to a close and Jeremy Corbyn was up. He wanted to know what the National Farmers’ Union, the Federation of Small Businesses, the National Audit Office, the National Housing Federation, Gingerbread and the Royal Society of Arts have in common.

An amusing list. Perhaps it had been written, or at least approved, by Seumas Milne, Corbyn’s Director of Strategy and Communications, who sits in the press gallery during PMQs.

For Milne, whose stern face usually recalls the incorruptible purity of Robespierre’s visage on a day when the guillotine is busy dealing with the enemies of the Republic, was laughing.

So a promising start by Corbyn, who was well above his usual level. What aspect of May’s record could all these organisations have combined to condemn?

The answer, he told us, is Universal Credit.

May knows her lines on Universal Credit. It encourages people into work, whereas under Labour’s system, some people got a hundred thousand pounds for doing nothing, and the money came from taxpayers on very much lower wages.

The Prime Minister mentioned a single mother who was told not to go back to work, because she’d be better off on benefits. She cited, in the manner of Corbyn, Roberta, Ryan and Naim, who paid tribute to the work coaches they get under the new system.

Corbyn proceeded to do her a good turn. He claimed you could see by “the sullen faces” on the benches behind her that Universal Credit has been an abject failure.

The sullen faces, which were not actually all that sullen, found their voice. A wall of noise enveloped Corbyn.

Here was tribal warfare, and May rose to the occasion, sounding almost as vexed as Margaret Thatcher did when attacked by some impertinent socialist. Above the roar the Prime Minister could be heard saying “Iranian State TV…police investigation into anonymous and threatening letters about the deselection of Labour MPs…institutionally anti-semitic…”

When she sat down, there were cries of “More” from the Tory benches, and sullen faces – genuinely sullen – behind Corbyn.

Universal Credit is a worthy subject, but one where the Prime Minister knows exactly what to say. Ian Blackford, for the Scots Nats, instead tried accusing her of being “unfit to govern” and “incapable of leadership”, and added that her backbenchers know this.

Blackford only gets two questions, and she sought to parry him by quoting the Scottish National Farmers Union. One could not help feeling that, as often happens, he had touched on a more sensitive spot than Corbyn – perhaps for fear of mocking laughter, he too is accused of weak leadership – had ventured to attack.

Chris Philp (Con, Croydon South), often in the past an ostentatiously loyal supporter of the PM, asked her whether it is true that in the negotiation with the EU, nothing – including the payment of a vast amount of money to Brussels – is agreed until everything is agreed.

The Prime Minister just about assented to that proposition, but in language which left her room for manoeuvre.

Philp turned in his seat, apparently seeking the approval of Jacob Rees-Mogg, who was just behind him. One could not help feeling that if May is to continue to enjoy the support of her backbenchers, the time is coming when she will have to strike a more resolute note about Brexit.