In general, I try to avoid really harrowing stuff on TV. There’s enough going on out there in the world without me sitting through death, disease and dystopian futures on screen. TV is escapism, my mind’s safety net, my evening respite, and tbf there was the occasional episode of Jonathan Creek that freaked me out. I like house renovation, lavish period drama and underplayed comedy, thank you. So why, when everyone else was tucking into the first episode of Bake-Off, was I watching a policeman look at a boiled head in a pot?

First of all, GBBO is, as far as I am concerned, past its peak. Nadiya was the zenith, and everything since then has been a slow, soggy slide into the nadir. Don’t @ me, it’s just how I feel. I’ll probably catch up with the crazy showstopper at some point, but for me, it’s overdone.

The other reason is that Bozo was on first, and I couldn’t bear to switch on linear TV in case I caught sight of that leaking scarecrow being jerked about by his puppet-masters – too harrowing by far. So instead, I was watching Des on catch-up, which I would have avoided like Covid, had my dad not told me it was ‘quite funny, actually, in a weird way’. The boldness of finding humour in the narrative of a notorious serial killer intrigued me.

Obviously, the subject matter is hideous and very much not-hilarious, but the whole thing is extremely well done, and thankfully you don’t get to see any of the murders/dismembering. David Tennant is a revelation, and I would like to lay claim to being one of his earliest fans, because back in 1994, I was obsessed with the BBC Two series Takin’ Over the Asylum, where he played a manic depressive working at a hospital radio station. God, that was a great show. Anyway, in Des he plays Dennis Nilsen, who, it turns out, seemed pretty normal; oddly normal; indeed, ‘quite funny, actually, in a weird way.’ Tennant looks uncannily similar to Nilsen and his delivery is dead-on (I looked up an interview to check) – a laconic, humming drone that makes him appear completely ordinary, or ‘unremarkable’, as DCI Peter Jay observes. His description of the killings is so conversational, so matter-of-fact, that it does become disturbingly comical. At one point, his solicitor turns to ask him why he did it. ‘I was kind of hoping you could tell me that,’ Des murmurs, as his interviewers sit shell-shocked in the fug of their own cigarette smoke.

Nilsen’s biographer, Brian Masters, is played by Jason Watkins, and I’ve loved him since he played an absolute bastard of a vampire king in BBC Three’s Being Human. Brian isn’t quite as brutal a character, but there’s something a shade shady about him being so entranced by evil. His rhoticism makes him sound strangely lascivious when he describes wanting to ‘compwehend’ the mind of a killer, adding an extra layer of grim fascination to the story. Brian is the one who tells Nilsen about the fate of his dog Bleep, which I already knew as I’d googled it almost immediately after she was taken away. ‘What happened to Dennis Nilsen’s dog?’ felt like a niche thing to type into a search engine, but it turned out many viewers had the same thought, and there were several handy articles explaining that she was put down. Nilsen is distressed by the death of his pet, a peculiar quirk given his lack of emotion when he discusses his victims, but I guess Hitler was fond of Blondie, too.

One of the things that struck me was how goddamn difficult it was to solve a murder in those days. No central database, no web searches, matching fingerprints by eyeballing them. But as a child of the 80s, I was pulled in by the period detail, the era lovingly recreated and heavy with nostalgia. Tiny details - rustic Hornsea pottery mugs in the police station, the dinosaur of a PC in Brian's study, the Bakelite telephones. It took me back to a simpler, cosier time – albeit a time when there were no women in the incident room, and no one noticed the Muswell Hill Murderer on the rampage.

We live not far from Melrose Avenue, the address where Nilsen committed so many of his atrocities. I’ve often wondered about it, because I remember it being for sale several years ago. At the time, I couldn’t imagine why anyone would consider buying a place with such a grisly history, but the couple who now own it have done it up, and remain unperturbed by its past: ‘we have sun everyday being south-facing’. It’s good that some light came out of all that darkness, and I must admit their kitchen does look lovely now.

There you go then. House renovation, lavish period drama, and underplayed comedy. I guess it has all of those things, in a way.

• Des, 3 episodes, ITV