There is a deep irony in the attempt by Met detective Micaela Rocha to get her fellow students at Peking University to demand that the institution sever all ties with Israel over its supposed “genocide” in Gaza. That, of course, is a grotesque lie. But Ms Rocha is studying in the capital city of a nation which is systematically carrying out a genuine genocide - of the Uyghurs in the north-western region of Xinjiang.

It is troubling that a serving police officer – even while absent from duties – should be involved in such a highly political campaign, and in spreading such malicious falsehoods. There will be those who, understandably, see the Met’s unwillingness to police the hate marches properly, see the behaviour of Ms Rocha, and then draw their own conclusions as to why the Met has been so bad.

The force’s appalling record in tackling the hate marches is made all the more galling when it showed last Saturday that it is perfectly capable of doing its job when it sees fit. More than 30 pro-Palestinian activists were arrested before the Pride march on suspicion of conspiracy to cause a public nuisance, after what was described as an intelligence-led measure. Nothing as subtle is necessary on the hate marches: the antisemitic slogans and chants are there for everyone to see. And yet the police stand and watch. This two-tier policing has to stop. The Met has shown that it will, sometimes, act. Now it needs to show that it will always act.