I suppose there should be a weight of expectation on a Doctor's final story, but I've never read a rave review of The Tenth Planet, or heard it referred to as an all-time classic. As a result of this I went into this with measured expectations and was blown away by episode one. We're in 1986, the south pole and there is a cosmopolitan mix of different arctic submarine officials who Ben, Polly and The Doctor get mixed up with. Then, there's the death of submarine officials and the big reveal - Cybermen! They receive the best introduction of any monster in Doctor Who so far, silently slinking on the far end of the screen, ignoring the screams of the helpless man trying to break into the TARDIS for safety; before coldly killing him off. I left episode one with my expectations quadrupled and surprised to see something of a "series finale" element in Hartnell's last story.

These Cybermen are creepy, half-human and all the worse for it, they are people who have adapted themselves to increase their lifespan, they have super-strength, but their adaption has gone out of control, they no longer have feelings. This enables them to control a room full of powerful people and sabotage their attempts to protect the base with only a couple of weapons and a cold outlook on the value of human life.

My main reservation is that the Doctor is not given enough to do, and with this being his last episode you want to saver every moment. Ben and Polly's involvement in the plot is variable. At points Polly is reduced to making tea for the boys. She does get to come up for a plan to stop General Cutler going too far in his efforts to destroy Mondas with a Z bomb, but its Ben that actually gets to carry this out. It is worth noting that we see perhaps the first credible and impressive role written for a black actor in the show though, going a small way to make up for the character of Jamaica in previous story The Smugglers.

As the end of episode three draws near the nerve-wracking countdown to the release of the z-bomb starts. This is a great cliff-hanger. Thankfully for episode four I have the BBC animation. In the final part there is of course one "unexpected" twist, something which has never happened before. The First Doctor's last few moments are astonishing, understated "it is far from being all over; I must get back to the TARDIS - immediately, yes I must go now; I must go at once; ah yes thank you; keep warm."

Ben and Polly bang on the TARDIS door, frightened about being left behind, meanwhile The Doctor is about to endure his first regeneration. He looks at the TARDIS console with his last few breaths, the machine whirring, something is happening! Ben and Polly run in to care for The Doctor who is now on the ground. This scene is some of the best Doctor Who has ever served up. William Hartnell disappears and Patrick Troughton takes his place. The First Doctor has left the building.