‘How long before I must retire, my work half done? If I could continue…’ This was the first Doctor Who I had on video (recorded off air, including the Children In Need links). In Special Edition form it was the first DVD I owned. I’ve read the novelisation numerous times. It introduced me to the first four Doctors. It’s impossible for me to be objective about The Five Doctors, because I love it more than any other episode.

I’m not blind to its faults – characters seeming to forget things that have just happened (Crichton forgetting he’s just been talking about the Doctor), or not seeing things in front of their noses (the Master holding a massive Cyber Gun in front of the Cyber Leader). Tegan looks like she’s wearing Minecraft; Sarah Jane looks even more absurd; everyone’s hair is awful; people have catch phrases (the Brigadier trots out his ‘all of them’ line twice, the second Doctor repeats his ‘you’ve redecorated: I don’t like it’ line from The Three Doctors). It’s easy to be very po-faced about this, but as fan service goes it’s a billion times more accessible than all those episodes with old enemies that don’t get a proper introduction.

Clearly, it gets more right than not. The Hartnell clip at the top of the episode is glorious, a real link back to the show’s origins – and a lovely nod to the return of Susan whose presence, like Billie Piper’s in The Day of the Doctor, draws a straight line between the title character of the first episode and the anniversary story. It’s lovely, even if Davison has to do a lot of heavy lifting in his non-verbal performance to suggest the Doctor is pleased to see his grand-daughter again. As a locum first Doctor, Richard Hurndall is fine, even if his grumpy, frail, sexist character isn’t very much like Hartnell’s developed take on the role (Twice Upon a Time owes more to this – including ‘The original, you might say’ – than the actual Hartnell Doctor). He makes a good contrast with Davison even while they look for opportunities to suggest they’re the same man (Tegan’s side-eye when they both ‘Hmm?’ her is classic). Plus his pineapple eating is an iconic image.

(As an aside: I used to pretend I thought Hurndall was actually the Other of New Adventures fame. Hence Susan recognising him as her grand-father, his claim to be the original, him recognising Rassilon’s voice, and his line ‘I wonder what happened to the Other’. Obviously I wasn’t being serious.)

Troughton gets all the scariest moments – fitting, for the “monster Doctor” of fan myth. The Cyberman grasping the Brigadier through a ruined wall and the Yeti stalking them through the caves beneath the Tomb of Rassilon are the episode’s stand-out behind-the-sofa moments. But the two of them also gets the best comedy – like the Brigadier criticising his singing, or when he glumly reflects they’re buried alive, and the Doctor chirpily replies, ‘Yes’ I’m afraid we are.’ There’s a persistent argument that his memory of Jamie and Zoe’s War Games fate proves the Season Six-B (post-War Games adventures) hypothesis. Not necessarily (maybe the Brigadier told him; maybe the Time Lords told him when they briefed him during the events of The Three Doctors).

Pertwee lives up to the “man of action” idea, zooming around in Bessie and improbably death sliding across the Death Zone. His pairing with Elisabeth Sladen is fortuitous, because it cements the third Doctor and Sarah Jane partnership. The 1990s BBC Radio plays are as much sequels to this story as the 1970s (I like to think when they leave in their TARDIS at the end of this something goes wrong, and they arrive back in 1975-80 for The Paradise of Death, explaining why Sarah seems to have two second meetings with the Brigadier). Fulfilling someone’s wish list, he gets to meet the Cybermen and face off against the Master. Here, Ainley gets his most Delgado-ish material, and is at his best because he has a genuine motivation to be in the story (selfish, of course), and actually gets to have conversations with the Doctors rather than just issuing threats.

Repurposing Shada for this was a great idea. I’m always half disappointed they didn’t lift the bicycle chase substituting the time scoop obelisk for Skagra’s sphere, but that would probably have given far too much time to what’s really just a sweet cameo. Obviously I wish Tom had consented to do this, but the fact his absence isn’t a nagging problem speaks to both the careful balance of the script, and that, perhaps, he wasn’t quite as all-important as he’d have liked to think.

In the original storyline, it was the Baker Doctor who went to Gallifrey to investigate. Instead, Davison gets to be the one who blows open the conspiracy and unmasks the traitor – which is how it should be. Perhaps it would have been fun to see the fourth Doctor hear Borusa’s conviction that the show can’t go on without him, but Davison’s great in his confrontation with Latham, whose sepulchral look and silent movie performance (all big, imperious gestures and exaggerated expressions) go a long way to making this incarnation more memorable and impactful than Leonard Sachs’. Davison more than holds his own in an episode packed with stars, playing it with a comic lightness and breezy assurance that are very refreshing. Dicks also ignores the tensions in the fifth Doctor’s TARDIS – the brief scenes of them all smiling, having fun on the Eye of Orion are the most relaxed and joyful there have been in about two years.

The story is simple, but effective. With Daleks, Cybermen, the Time Lords and the Master it incorporates all the biggest threats from the earlier Doctors but manages to do something new – revealing a dark secret at the heart of Time Lord civilisation and, in Rassilon, adding something quite interesting to the mythology: not a tragic Greek god like Omega, but a trickster, a game-player, someone who might be evil or might be good depending on circumstance. And it concludes the 20th Season’s strange obsession with the horror of longevity – ‘Immortality was a curse, not a blessing’ – in style, wrapping it up in a neat package, and freeing the Doctor in his fancy new control room to look forward to adventures unencumbered by the past.

Next episode: Warriors of the Deep