The return of Ambassador Brodny makes this a sequel of sorts to the middling season 4 episode Two’s A Crowd. Yes, it’s another Levene story with a sci-fi premise being proved to be a hoax (invisibility, rather than Venusian invaders or time travel) but in a sense he has crafted the perfect sequel. Once again, Brodny plays the role of the dim-witted insider who must be fooled to convince the opposition so it’s exactly the same set up. Added to which we have the third of Roy Kinnear’s appearances – this time as a mad scientist, but for once a tolerable one, partly because he gets a decent lab but mostly because he does the comedy stuff so well. And between him and Warren Mitchell, this is certainly a comedy episode. So on that level it works. But the more comedic the episodes become, the less the Avengers is a thrilling adventure (which it still was at the time of Two’s A Crowd) and the more it becomes a parody of itself.

Visually, things make a slight improvement from the previous colour episodes: there is some imaginative photography, and this one does look good.

And though once again the premise has a kind of insane plausibility, the realisation is once again slapdash. No effort has been made on the science, and even the simple technology that is used to project the effect doesn’t explain everything. For example: though we know how the embassy and the records office were set up, how was the playground rigged? Bertha’s wheel? Mrs Peel’s door? That’s even before you ask the question, was all this really worth the effort compared to any other ploy to bamboozle the Brits the Russians might have employed.

Then there’s the question of clothes. Was the invisible man supposed to be naked, except in the two or three scenes where he was dressed, gloved, and headless? So he was naked in the records office? And after Brodny found him sitting in his chair he disrobed and returned to his chair before Brodny came round…?

Ah well. I do still like Ambassador Brody’s please not to be sent home… “I have tickets for the next Beatles concert. And I am learning to play cricket.”

Subtitle: “Steed makes a bomb. Emma is put to sleep.”

We’re needed: Mrs Peel see’s Steed’s message in her microscope.