After a couple of very straight episodes, this is a throwback to the silliness of season 5 – perhaps a reflection of this being produced a year earlier. Philip Levene’s scripts in that season started by taking sci-fi concepts – for example invisibility – and having a hoaxer convince victims they were real. Later, he didn’t bother making them hoaxes – he just ran with the sci-fi concepts. Here he revisits the invisibility notion, and just make it real too. The gloss is that it’s like chameleons (the magic formula is supplied in bottles of ‘Lizard Vodka’) but the production completely fails to pull that off: the lack of care with shooting angles means we can see through people when they are ‘camouflaged’ and it even ‘works’ against complex backgrounds (eg. Steed’s bookcase). It works on clothes as well as hair or skin – even if those clothes are brightly coloured tracksuits…

Peter Bowles makes the fourth and final of his Avengers appearances. It’s not a triumph like Dial a Deadly Number but its diverting to see him play against type – a thuggish Russian rather than a smooth Englishman.

Steed’s social circle features again: he introduces two of his close friends to Tara and they party until 5am in his flat. But when he makes a very sincere toast, you know it’s going to be curtains for both of them.

Steed expresses a preference for a S&W Magnum, though I don’t think we’ve ever seen him with one.

Captured spies are given a liquor ration and treated well “otherwise we’re no better than they are” with the prison disguised as a monastery (the first such retreat since season 2’s Dead on Course?) But as they escape, the guards narrow their focus to eventually their one remaining prisoner – I couldn’t but be reminded of Michael Palin’s Escape from Stalag Luft 112B.

One more episode to go…