I recently had cause to watch "An Unearthly Child" for reasons which may become obvious one day or not (as the case may be) and during the course of it twenty five things popped into my head. Because I’m a stickler for rules I’ve had to keep one of them to myself. It was a tired one about cave men wearing underpants. You’ve not missed anything by my strict adherence to twenty four of the following THINGS~!

1. The book about the French Revolution that Barbara gives Susan is season 1’s "Bad Wolf". The lingering close-up was a bit subtler than most of the Bad Wolf references but they wrapped up the story arc in the final adventure of the season so everyone was happy. Those that weren’t could pop along to the cinema and watch "Don’t Lose Your Head".

2. Why does Barbara ask Susan how many shillings are in a pound if it’s so obvious? Were questions designed to flush out spies and foreigners a standard part of early 60s teaching?

3. It’s not her fault, probably, but it’s no wonder they think Susan is odd – she gets hysterical for no reason during those bits of her life when she’s meant to be mysterious. "It’s IMPOSSIBLE" she blubs while the rest of the class get a bit embarrassed and wonder if her telekinetic powers are going to send their pencil cases flying around the room.

4. And, seriously, who needs to use D and E to solve a simple geometry puzzle anyway? Short of using the Tardis to go forward five minutes and a few feet to the left in order to hear Ian’s answer, it’s a bit over the top.

5. Pity the poor policeman who not only launches the single most iconic television programme of all time and gets no credit for it, he was obviously so bad at carrying a torch and not speaking that he was recast between the pilot and episode 1. "Implausible official snooping" was the explanation given some years later when his granddaughter got a question asked in Parliament.

6. I genuinely get depressed when I think about how Ian and Barbara are meant to be younger than I am now. They’ll always be far more grown up and sensible than I’ll ever be.

7. I really want to know what that girl whispered in the other girl’s ear to make her laugh slightly. There has to be a novel that explains it somewhere. Hopefully it’s something like "Susan says we can use her grandfather’s junkyard later if you fancy a cuddle".

8. They’re 15 – it would be so normal after all.

9. Is it me or are the Common Men doing all the work while John Smith takes all the credit? It’s their guitar playing that got them from two to nineteen, nineteen to two. He does nothing. I bet they split up in a fit of bitterness and there are now three different groups of Common Men and at least two old codgers with gravelly voices claiming to be John Smith.

10. Why does Ian think the Tardis is "alive" just because it’s vibrating? Lots of machines vibrate without being alive. Actually, most machines vibrate without being alive. Don’t all machines vibrate without being alive? Vibrators are a good example to start with.

11. I want to know what it felt like to see the inside of the Tardis for the first time. Not as Ian or Barbara – just as a viewer who didn’t know what was inside the police box. Were they overawed? Baffled? Or did they think it was silly? We take it for granted now and it’s become a joke to see the new companions freak themselves out when they see it but there was a first time for shocked viewers as well and I missed it.

12. Why does the Doctor not just let Ian and Barbara go? They might tell someone about the space ship they found inside a police box that was in a junkyard but which has now vanished. But it’s probably a tale that’s less likely to draw attention to himself than, say, lighting the Olympic flame.

13. I mention it every time but from the Five Faces repeat until well into the 90s I thought the shadow that falls over the ship was a dinosaur. I didn’t realise the truth the first time I saw it on video or UK Gold, or the second, probably not even the third, fourth or fifth time.

14. The big fight between the one that looks like Derek Newark and the one that is Derek Newark is shot on film and is considerably better for it. Every subsequent studio fight pales by comparison. They spent a bit of money on this story and it shows.

15. Why is the old man of the tribe – Aletha Charlton’s dad – younger than the young bucks, who are old, who want to take over the running of the tribe? It makes literally no sense.

16. And who glued Eileen Way’s teeth together?

17. The Doctor and Barbara seem to be having a "who can have the biggest hair" competition. The Doctor is winning.

18. The Doctor gets the one who only looks like Derek Newark thrown out of the tribe because his knife has blood on it. Given that the one who only looks like Derek Newark has killed animals recently so the tribe can eat, isn’t not unreasonable that his knife would have blood on it. As evidence it would only work on very stupid people. And I say that as a vegetarian with a law degree.

19. The cavemen sequences aren’t actually as boring as people think. It benefits from being 1+3 episodes rather than stretching it to four episodes and if you ignore that all they ever talk about is making fire and arguing about who should be their leader, it’s not a bad little story. The Conservative Party under John Major spent seven years doing the exactly the same except they already knew how to make fire.

20. Actually, I want to give it a lot of credit for the way they get across how primitive these humans are. Not by having them grunt or speak like Tarzan but by the confused looks they given when they try to understand complicated (and unnatural) ideas like friendship, compassion and mercy. It actually works and puts every other attempt the series would have of portraying primitive cultures to shame.

21. I was waiting – when I rewatched it recently – for the dramatic moment when the Doctor makes to kill the injured Derek Newark because it is a pivotal moment in the character’s development. In reality it is a tiny flicker of action that could easily be taken any of a dozen ways. Apart, obviously, from the drawing-a-map idea the Doctor makes up for Ian’s benefit. Imagine a map drawn by one of these cave men. It would have a mark "here" and another mark "there". That would be their cartographical limit.

22. The burning skulls are cool. If that happened today we’d be able to buy those. In boxes of four, naturally. With really obscure batteries and a plasticy smell in place of the proper rank odour of burning corpse fat.

23. Oh and wouldn’t it be cool to be able to buy a replica of the Doctor’s pipe? The licensees would force the producer to keep the Doctor smoking and he’d have to get a new pipe every season.

24. I love how the Doctor blathers on about data (to rhyme with "barter" of course) and no one buys it – they just tell him he doesn’t know how to work the ship and he grudgingly admits it. If only Susan subtly worked the knobs and switches for him like River Song does – that would make her even more incredibly annoying than she already is.