Every June solstice, as summer stretches ahead, some miserable bastard always say “well, the days are getting shorter”. Is there a more perfect Avengers episode than this? I think there is not ((although there are a couple of contenders)) and an irksome voice in my head points out that means it’s downhill from here. The Avengers won’t ever be as good, and, because no television has ever bettered The Avengers, it’s downhill for all television from now on. On the positive side, as far as The Avengers is concerned, we have a plateau (albeit with a few pits and hollows) before the decline, and even then it will be a gentle one.

Where to start? Graveyards full of jamming equipment, coffins being carried into operating theatres (“Forceps. Scalpel. Blowtorch.”), Steed tailing a hearse, a hospital for ailing railwaymen, Mrs Peel in a nurse’s uniform… No, the highlight has to be Ronald Fraser’s train-mad philanthropist and his miniature ride-on railway. His house, with its booking office entrance hallway, trackbed carpet, a wreath for each closed railway line, and – oh – the simulated travelling dining experience… perfection.

And then we have a fight aboard the miniature train, and Mrs Peel tied to the narrow gauge tracks (“What is that young woman doing tied to the railway line? She’ll break the engine!”). It wouldn’t work if the actors didn’t take it totally seriously but they do! The ‘silent movie’ soundtrack nods to Buster Keaton style trope they’re sending up, but there’s no on-screen acknowledgement of the absurdity of the scenario.

In other respects, this episode maintains the high production values (if anything, the standard is even higher). The soundtrack is again, wonderful. Also the lighting and photography.

Steed’s got a new apartment. Once again, there’s no way this can be the same place we’ve seen before (though no address is given).

Mrs Peel identifies a selenium rectifier – whatever her field is, she knows about electronics.

The transport for this week’s tag scene is- straight from the main plot – the miniature locomotive John of Gaunt.

I haven’t even mentioned some of the other guest stars yet… Wanda Ventham (Sherlock’s mum) and Steven Berkoff.

I just want to watch it again, straight away. So, so wonderful. Downhill from here? Well, it’s going to be a hell of a ride.