With one simple offer Keir Starmer left Boris Johnson floundering during PMQs

One of the most effective forms of attack is to agree with one’s opponent. Keir Starmer deployed the tactic of bipartisan reasonableness to devastating effect today, leaving Boris Johnson so badly winded at Prime Minister’s Questions (PMQs) that it looked as if the Labour leader were running the country.

Starmer started by reminding the prime minister of the mood of the House when it paid its respects to Sir David Amess on Monday and asked for a commitment to start the passage of the Online Safety Bill “by the end of this calendar year”. Starmer said: “If he does, we’ll support it.”

Johnson was forced to be on his best behaviour: “I thank the right honourable gentleman for the spirit in which he has approached this issue and I echo what he says about the need for cooperation across the house.” He duly promised to bring the bill forward before Christmas, as he had been told.

Starmer thanked him and then asked why the directors of social media companies, who “facilitate and nurture a subculture that cheerleads for terrorists”, would not face criminal sanctions under the government’s current proposals.

Johnson responded that he would “continue to look at ways in which we can toughen up those provisions and to come down hard on those who irresponsibly allow dangerous and extremist content to permeate the internet”.

The Labour leader noted those two gains. “We’re making progress,” he said.

He then asked the prime minister to implement the recommendations of the commission on countering terrorism, set up after the Manchester Arena bombing in 2017. He quoted Sir Mark Rowley, the head of the inquiry, as saying that he had had no feedback from the Home Office on his proposals. Priti Patel, the home secretary, was sitting next to the prime minister and offered him some advice about his reply.

We don’t know what the advice was, but Johnson said that 31 terrorist plots had been foiled since 2017. He then went on to attack the opposition, saying that the government would not allow terrorists to be released early from prison: “That was one of the most important things this government passed and which that party opposed.”

This was cheap politics, and everyone in the Commons knows it is cheap politics, because they know that Labour opposed the legislation for reasons unrelated to the early release of prisoners. Starmer swung effortlessly into the saddle of his high moral horse. “After the week we’ve just had I don’t want to descend to that kind of knockabout,” he said.

The Conservative benches were silent, realising that he was in the right, and Starmer drove his advantage home by saying: “I’m taking my lead from those on the opposite benches on Monday, and what they were saying about the need to tackle this: either we take it seriously and go forward together, or we do a disservice to those that we pay tribute to.”

The prime minister looked sulky, not used to being outwitted by the Labour leader. “I’m all in favour of a collegial and cooperative approach,” he said, grudgingly, “in which case I think it would be a fine thing if the opposition would withdraw their opposition to our measures to stop the early release of serious extremist and violent offenders.” Then he added the telltale phrase of the chastened loudmouth through the ages: “That’s all I’m trying to say.”

In other words, I realise that I have got the tone wrong and that the leader of the opposition has made me look like the trivial person he said I was.

Starmer had deployed the collegiate spirit to devastating effect, building on his most effective line when he paid tribute to Sir David Amess on Monday: “I want to lean across, to reach across and to acknowledge the pain that is felt on the opposite benches.” It was the prime minister who broke that mood with his party politicking, causing his own supporters to recoil with an unspoken, “too soon, prime minister, too soon”.

All in all, it was one of Starmer’s most effective outings at Prime Minister’s Questions, making Johnson look tacky while presenting himself as the champion of the fight against terrorism. “I’ve prosecuted terrorists and I’ve prosecuted extremists,” he said, advertising again his credentials as Director of Public Prosecutions. The contrast with his predecessor, who equivocated over whether the police should have a shoot-to-kill policy for terrorists, could not have been more striking. But the prime minister could hardly point that out, because that would draw attention to the fact that Labour had changed.

As it was, Boris Johnson was left with nothing of substance to say.