The Green Death is everything Doctor Who should be.

The Doctor is on excellent form, working with others - including a great working relationship with Professor Jones, when it would be so easy to write them as competitors. His relationship with the Brigadier has so much depth to it now, compared with Spearhead From Space, and really shows the value in having long-running characters. Their points of view might not be exactly aligned, but they listen to each other and show proper respect.

Jo Grant really is at the centre of the story, and there's no way you could replace her with any other companion, the way you could with so many lesser stories. Her interactions with everyone - as superbly played by Katy Manning - are supremely realistic. Things might seem a bit sudden on first watching, but isn't that a characteristic of Jo herself? Right from her first scene you could see the makings of it. And that ending...

Another great quality is how the story doesn't take itself too seriously. There is some horror with what's happening to affected characters - what great special effects! - but the story knows when to have fun too. Pertwee gets to do some great dressing-up. There some wonderful moments where the editing creates jokes in itself. Even the villain is inspired, and a true step up from similar ones seen previously.

Yes, some of the special effects are a bit rubbish - my only memory from watching a repeat of this when I was a young kid was of the really bad green-screen stuff - but when you're swept up in the story that only adds to the charm. And let's face it, it wouldn't be Classic Who with a bit of naff as well.

I'm not sure I would recommend this as a must-watch for people new to Doctor Who, as the real joy is in the relationship between the Doctor, the Brig and Jo, but my goodness it is an absolute delight.

There's some lovely ideas in this episode. It feels a lot like a Third Doctor/UNIT story (where was UNIT during all of this?), and the foundations for what would become a great show are definitely there. It's just a shame the tone is very uneven, and there is lots of overacting. Also the direction with all the weird camera movements gave me a bit of a headache, and thank goodness one particular character didn't make it to the main series.

The first page is fantastic. And then...

I couldn't tell any of the characters apart. Who was talking? Turlough? Tegan? Some nameless character the story hasn't bothered to introduce?

And to cap it all off, the villain is just annoying.

Do you know those stage productions which are deliberately artificial? Shakespeare but all lines are spoken facing the audience, that kind of thing? I think the term is the ‘distancing effect’. This story is absolutely full of it, and for me personally that was the highlight. Extremely tight camera angles on corridors; characters saying Important Things, not so much to each other but to the room; a clearly-stated Message (drugs are bad, kids!); a bewildering choice of Dutch/South African accent; the camera left on a scene just a little too long whenever K9 does something… I could go on. All this has the effect that you are watching Something Special (like Morgus’ addresses to camera in The Caves of Androzani), and the setting – two ships merged in hyperspace, a projection machine that doesn’t so much project as capture, and a decent story about drug trafficking and its effects – has potential for a fantastic episode.

On the other end of the scale, we have full-on camp. The passengers on the Empress are dressed like they’re about to go for a trip to see Niagra Falls on a gay cruise. The customs agents’ uniforms have an inexplicable glittery pattern suggesting they were borrowed Nazi uniforms from a production of Springtime for Hitler, or else they were planning to attend the local Pride parade once their mission was over. The Empress security guards look like they have never had to confront anyone in their lives, and hope never to have to – and of course they don’t die but Die, with Facial Expressions and Gestures. As I said – CAMP. Which is not uncharted territory for Doctor Who, and could also have made for a great, if less memorable, story.

The problem is, these two aspects are diametrically opposed to each other, and nothing truly meshes. The production was beset with problems, including the original director Alan Bromly being fired halfway through, and perhaps it is this which has caused the difference in styles. One minute you have a corridor chase through a ship where all the corridors look suspiciously the same; then we see vrax slowly take hold of Rigg, and the horrors that entails.

All the usual elements are there, with Tom Baker as fantastic as ever and a good supporting performance from Barry Andrews as Stott, who had been accidentally transported not so much from Eden but an episode of The Wire 25 years in the future. It’s just a shame that the serial can’t make up its mind what it wants to be.