Theresa May has just told the House of Commons that there is ‘no alternative conclusion’ other than that Russia was responsible for the attempted murder of Sergei Skripal. She said that Moscow’s response to the UK’s request for an explanation of what had happened in Salisbury had demonstrated ‘complete disdain’.

In response to the incident, the government will expel 23 Russian diplomats who it believes to be spies. The UK will also break off all high-level contact with Russia – so there’ll be no British dignitaries at the World Cup this summer – and pass its own Magnitsky act.

This UK response is not small. But it is clearly designed so that the government can respond to whatever Russia does next. I suspect that if the Russian respond by expelling 23 British diplomats, the Russian ambassador may well be kicked out—for instance.

In response to Theresa May, Jeremy Corbyn delivered one of his weakest Commons performances. Reading in an uncertain manner from his text, Corbyn raised a series of questions about the evidence and the need to build a diplomatic coalition. But he singularly failed to say that he believed Russia to be responsible for this attempted murder.

May, who is normally a cautious Commons debater, then went for Corbyn. She pointed out that there was consensus among the UK’s allies and on the backbenches of both Houses that Russia was responsible, and that Corbyn is outside it. This point was then reinforced as the SNP, the Lib Dems and a slew of senior Labour backbenchers vigorously backed May’s position.

I suspect that Corbyn’s stance on this will reignite his troubles with the parliamentary party, which have largely been kept under wraps since the snap election. Listening to Pat McFadden, Yvette Cooper, Ben Bradshaw and the rest, one was left wondering how they could make Jeremy Corbyn Prime Minister.