While I was writing my essay on the British far left during the Cold War, I wanted to make the case that the moderate left has been too accepting and tolerant of the far left. (My own feeling is that I look at the Soviet Union with horror. It was a relentlessly oppressive regime, perhaps genocidal. Any suggestion of emulating it should ideally be well outside the Overton window.) And the examples that I took were a couple of articles in The Guardian, but I felt like that perhaps wasn’t strong enough evidence. After all, the papers aren’t always too discriminating about what they’ll print.

I’ve now realised how I could have made that point another way. Try searching for “hammer and sickle” on Amazon. Compare with searching for “swastika”. It’s clear what’s inside the Overton window and what’s outside.