Boris Johnson and Keir Starmer know that the stakes are high ahead of their first PMQs clash

The mind games may have already begun as the prime minister looks to keep the Labour leader guessing, writes John Rentoul

Sir Keir Starmer, left, is likely to face Boris Johnson at the despatch box at PMQs for the first time (PA)

It says something about the forthcoming Prime Minister’s Questions that Boris Johnson’s official spokesperson wouldn’t confirm in advance that the prime minister would actually be taking part in it.

I assume this was a tiny tactical device designed to keep Sir Keir Starmer guessing as to whether he would be facing his principal opponent for the first time at noon tomorrow, or his substitute, the foreign secretary. It is the equivalent of sledging: trying to put your opponent off.

The prime minister could pay no higher tribute to the new leader of the opposition. Why play such games unless Johnson thinks that he is up against an opponent who poses a threat to him?

I doubt if Starmer will be distracted. He will be nervous enough about his first engagement with a formidable adversary: someone with whom he will struggle over the next four years as they compete to persuade the voters that they should hold the top job in the years after that.

The Labour leader will have prepared for this moment, possibly more thoroughly than he has prepared for anything in his life. He has a strong team around him who will have tried to think through all the angles.

My guess is that they will have rehearsed how Starmer would deal with all kinds of attempts by the prime minister and others to throw him off balance. Fortunately for them, the socially distanced chamber reduces the scope for disruption.

There will be no wall of noise, which is the most surprising thing about being physically in the chamber in normal times – the sheer volume of the shouting from the other side. There will be no heckling, and there can be no stunts from the Scottish National Party – they can hardly stage a walkout from the chamber if they are not actually in it.

So it will be a straight contest of wits, in the atmosphere of a courtroom rather than that of a theatre or debating chamber. That should play to Starmer’s legal style. What also helps the leader of the opposition is that he has six questions, giving him more opportunities to follow up evasive answers – while journalists at the daily government briefing are able to ask only one follow-up question.

The big picture, though, is that Starmer has to appear to be supportive of the attempt to control the coronavirus epidemic, while sowing the seeds of doubt in the mind of the undecided voter as to whether the prime minister knows what he is doing.

This may seem easy to those who are convinced Johnson is a fool or worse who has mishandled the crisis from the start. For them, the only hard part of Starmer’s job is to choose which of the many government failures he should condemn. But Starmer’s mission is not to preach to the converted: he needs to do something much more difficult, which is to ask questions that will help persuade some of those who currently tell opinion pollsters that they approve of the prime minister’s handling of the crisis that he is not doing such a good job after all.

That will take immense skill and patience, but those are qualities that Starmer has already demonstrated, and they are part of the reason party members elected him leader. Johnson knows it too, so I think he too will have prepared more than usual for this session of Prime Minister’s Questions.

In a way that hasn’t been true for five years now, the prime minister knows that his job may depend on it.