Sadiq Khan first weighed in on the Labour antisemitism row debate in April this year, when he issued a challenge to Jeremy Corbyn to “walk the walk” in tackling the problem.

Yesterday on BBC Breakfast, the London mayor expressed his disappointment that the row was still rumbling on and declared: “It’s really important that the Labour party leads by example. In City Hall since I became mayor for example we used the definition of antisemitism used by groups around the world. I want the Labour Party to adopt that position.”

But apparently that’s not good enough for politican-turned-Evening Standard editor George Osborne.

“When a significant group of Londoners feel threatened because of their race and religion, you would expect Mr Khan to speak out loudly in their defence,” states today’s Evening Standard editorial. “So where is our Mayor?”

The editorial the helpfully goes on to remind readers that Khan was backed by Momentum when he became Labour’s mayoral candidate and that he signed Jeremy Corbyn’s nomination papers for leader, before adding: “It is all the more important, therefore, that the Mayor speaks out now.”

The baffling attack has gone down badly with pals of Khan such as ex-Labour MP Michael Dugher, who called it “rather unfair” and noted that Khan has “consistently spoken out about antisemitism in Labour”.

Similarly unhappy are groups such Jewish Labour Movement who called Osborne “completely wrong”.

Sorry @George_Osborne you are completely wrong. This is an unfair & ill informed attack on @SadiqKhan. He "spoke out" against antisemitism in Labour just yesterday and has done on many occasions. He has been a consistent ally & supporter of @JewishLabour. https://t.co/OsXbYCdpDz pic.twitter.com/I0VGSMArMS — JewishLabourMovement (@JewishLabour) August 16, 2018

What could Osborne possibly be up to? One possible answer is that the former Tory chancellor is doing a bit of early bidding for the Tories as they select a candidate to fight Khan in the 2020 London mayoral contest.

If so, it marks a radical departure from the stance that he took earlier this year.

“If you assume that we are going to back some Conservative mayoral candidate in 2020 just cos they are a Conservative, forget it,” Osborne said at the AdWeek conference in London.

“We will make a judgement on behalf of the people on London about whether Sadiq Khan should get our support for a second term or whether whoever the Conservative candidate is gets that.”