When I was five years old, my record collection consisted of just one LP: TV Favourites and Other Children’s Songs. I can still see the cover (I just Googled it): a painting of Rupert the Bear, the Pink Panther and Dougal from The Magic Roundabout. But I didn’t care about them. Only one thing interested me about this record, and that was Side 1, Track 5: the Doctor Who theme.

Nothing sounded like the Doctor Who theme. The unmistakable throb of the dum-de-dum bass line, foreboding and thrilling at the same time, accompanied by that strange, undulating wail, which is then slowly consumed by a rumbling, whooshing crescendo which leads inexorably to a liberating scream of …

Me: OOOOH-EEEEEEE-OOOOOOOOH!

My record sounded nothing like that. It was a bad cover version, the Doctor Who theme arranged for parping Stylophone, piccolo and snare drum. I knew it was wrong (there were trumpets in the middle eight, for heaven’s sake), but it was still marginally better than nothing, so I played it to death, at least until it was time for me to hear the real thing again, on a Saturday afternoon, from a mono speaker on our television set.

The Doctor Who title sequence was terrifying but compelling. The first title sequence I remember begins with a rippling sea of coloured lights, which twist and bend themselves into the face of a man with an enormous nose, silver hair, and a very thin smile. His face turns a bright shade of green, and then it melts into the background as the words DOCTOR WHO bleed magically onto the screen. The words fade and a spinning blob takes over, rotating backwards and forwards, hypnotising me, drawing me in …

However, just when I got used to this title sequence, the people who made Doctor Who decided to change it.

The music was exactly the same but everything else was different. A tunnel of tiny stars merge to form a turquoise whirlpool (aka the space-time vortex) from which the Doctor’s face appears once again, only this time he isn’t smiling. The Doctor looks upset.

Jon Pertwee’s Doctor scared me, and it wasn’t just because his face loomed out of the space-time vortex like some elderly ghost. It was because the Doctor could be more frightening than the monsters. When he wasn’t barking at the villains he was shouting at his assistants, especially the Brigadier, who always seemed to be in his bad books. But there was something reassuring about the Doctor, too. Yes, he was intimidating and strict, but he was also the only person in the room who could stop the monsters. So I trusted him, even though the only time he looked truly happy was when he was beaming from the wrapper of a Nestlé chocolate bar. The Doctor definitely didn’t look very happy when he was being flung backwards into the space-time vortex in this new title sequence, his arms folded indignantly across his chest.

But if I couldn’t identify with the Doctor, I could latch on to his assistants. The Doctor was never alone. There was Jo Grant, the girl from the swamp. When she left, Sarah Jane Smith replaced her, and she was both beautiful and brave. In fact the Doctor had loads of friends, far more than I did. Most of them were soldiers who liked to blow things up. They asked the questions I wanted to ask, they faced the monsters I dared not face, and they stuck by the Doctor through thick and thin, even though he was often really rude to them.

The Doctor’s friends never appeared in the Doctor Who title sequence, which is a shame, but when the programme makers decided to modify that whirling vortex again a year later, they chose to incorporate his principal mode of transport.

The Doctor’s TARDIS is a space-time machine that is bigger on the inside than it is on the outside. It also looks like a police telephone box. I got my head around the first concept remarkably quickly, but the significance of the Doctor’s choice of a blue box puzzled me for ages. There weren’t any police boxes in Coventry in the 1970s so I never got to pretend that the Doctor’s TARDIS had suddenly materialised at the bottom of a suburban street, although I did feel a rush of excitement whenever I passed our local police station, mainly because of the signage and the fact that its doors were painted a similar shade of blue.

One day, I learned that the Doctor’s time machine looked like a police telephone box because it didn’t work properly. I can’t remember who told me this – it might have been the Doctor, an episode of Blue Peter, or perhaps even my mum – but it made perfect sense. Stuff broke down all the time in the 1970s: the telly, the buses, even the electric went on the blink every now and again. The TARDIS was supposed to blend into its surroundings but it had got stuck in the shape of a police telephone box in the 1960s, back when police telephone boxes were still relatively commonplace. The Doctor seemed not to care that his TARDIS didn’t work properly in much the same way that my dad seemed not to care that the central heating in Lavender Avenue didn’t work properly. You had to grin and bear it in the 1970s.

The next thing to appear in this title sequence is the diamond-shaped logo. A logo that was notoriously difficult to draw on a pencil case without the aid of a compass and protractor. And then the title of the story appears in white, bold letters – a warning of what to expect: planets infested with spiders, invading dinosaurs, or a monster on Peladon. But every once in a while, the title would contain a word that I recognised. A word that would send me over the edge …

The first time I encountered a Dalek was outside Coventry’s indoor market. This Dalek – bright red with blue orbs – looked incongruous next to the double-decker buses, tractors and a choo-choo train, and I only sat in it when all the other vehicles on the motorised merry-go-round were occupied. The Dalek didn’t scare me. I just didn’t understand it yet.

This lasted until I saw the Daleks on television. It was the voice that did it. That grating, hysterical staccato, bubbling with anger and hate. The Doctor could be a grumpy sod sometimes, but the Daleks were angry all the time. Utterly unreasonable, malicious and cruel, they even had their own catchphrase, and while I knew you couldn’t imitate a Dalek perfectly – that was the whole point, they didn’t look even remotely human – if I stuck my arms out like one and talked like one, people seemed to fall for it. EXTERMINATE!

The next time my mum took me to the market, and we approached the merry-go-round, I felt a mixture of excitement and dread. But even though this strange pepper pot-shaped object had a sinister aura about it, I never wanted to sit in a tractor or a choo-choo train again.

The title sequence over, I am immersed in the world of Doctor Who. It’s Proustian, Pavlovian, even Freudian: the unearthly sounds and hallucinatory visuals have primed my brain to embrace the impossible. And for the next twenty-five minutes, the real world no longer exists.