The BBC has, to use a technical term, smashed it: smashed the autumn ratings war, that is, with Bodyguard outpacing its ITV rival (a slightly tired, though big name Vanity Fair) by more than double the amount of viewers. But it also smashed the past decade, with the largest audience for a drama debut since 2006, and its own career-best: people haven’t lined up for a BBC debut in these quantities since records began.

Before we do the obligatory spoiler alert, is this show, in fact, unspoilable? Not because you get to see Games of Thrones’ former King in the North’s arse, but because, defying the times and all the technology in them, people are watching it live simultaneously? This isn’t precisely true: 3.6 million iPlayer viewers were added in the week after the August bank holiday, to bring the total for episode one up to 10.4million. But it’s not a box-set story, slow to take off but with a very long tail. We’re back in the world of the watercooler – a bygone era when we all watched TV at the same time, and had proper jobs where you got your own desk (and water).

Assuming, then, that you’ve seen it, for the half dozen who haven’t: Richard Madden is bodyguard to Keeley Hawes’s home secretary. Every known peril is effortlessly spirited up, from an attack on Madden’s children’s primary school, to a conspiracy that raises for Hawes the demon that maybe her own police force would prefer her to cop it. It’s not what you would call cliche-free – ex-wives have always met someone at the worst possible moment, the trope of the troubled cop who can save everything but his own sanity is very well worn, and the Muslim as go-to baddie is all those things, but with more consequence. The actor and writer Riz Ahmed described the cultural trajectory he has lived through to the New York Times last week: “In the 80s we were called black, at least politically black. In the 90s, we were ‘Pakis’. But after 9/11, suddenly we were Muslims.” Did TV drive this, or respond to some other force, some demonisation bubbling up from tycoons in older media? I don’t know, but it is depressing when drama premises itself on the idea of the Muslim terrorist. It doesn’t matter that the next act of terror is committed by a white guy; it still feeds the beast.

But if I said that interfered with my enjoyment, that I hadn’t just parked it all in order to concentrate better, I would be lying. Everyone is talking about it, and everyone has a view. A friend, who is a makeup artist, has a finely detailed critique of Madden’s foundation. I was recently on a politics panel with the conservative commentator Tim Shipman, who was able to explain the relationship between the police and MI5 in Bodyguard with far more confidence and enthusiasm than he could say what “Canada-plus” was supposed to mean.

Bodyguard … it’s got bedroom scenes too. Photograph: Sophie Mutevelian/BBC/World Productions/Sophie Mutevelian

It has done something to us, this show; it has cast us back to the earliest days of 24, when you watched a programme the minute it was on because you really couldn’t wait any longer. But it takes us back even earlier, to when TV could thrill you all it liked, but at the same time be curiously comforting, the events it conjured up manageable, its dangers within the scope of human ingenuity to avert.

Let it be noted that the show’s creator and writer, Jed Mercurio, puts most of Bodyguard’s pull down to the performances of Madden and Hawes, and they are, without question, exceptional. Madden has been hovering over our screens like a premature death, like a relationship that finished before it was really, you know, over: the great tragedy of Game of Thrones as drama is that, being based on the books, it repeatedly kills off characters before you are ready to lose them. Bespoke TV writing would never do such a thing: part of the reassurance of Bodyguard is that you know, whatever happens, David/Dave will definitely not die.

Hawes brings to her morally ambiguous role what you somehow divine as a deep moral purpose. She is a conviction actor. It is something to do with the wisdom in her face, a sagacity that surfaced on Twitter with a pleasing, no-nonsense response to a Mail on Sunday article about how she had lost a stone to play the part because, an unnamed source said: “This is a really sexy role for her, she wanted to get in character and look amazing.” Her reply: “Um, no, I didn’t. #whowritesthisshite?”

But Mercurio, too, is exceptional, with a casual mastery of pace and character that render the inevitable debates about Bodyguard versus Line of Duty (was the latter more sophisticated, because it was a bit less hooky? Or is the former more daring, because it gets straight to the dark heart of everything?) rather irrelevant. There is no accident to a Mercurio script. If you are still biting your nails an hour later, that was his design.

Hawes brings to her morally ambiguous role what you can somehow divine as a deep moral purpose

The era of Bodyguard is ambiguous: technically, it’s contemporary, but it feels nothing like the politics of now. There is none of our current febrile atmosphere, the sense that nobody knows where anything is headed: the House of Commons in Bodyguard is very much that of 10 years ago, where MPs’ dark motives weren’t written all over their sweating faces, and could only be surmised. Somehow you can tell that this is a world in which Donald Trump hasn’t happened, in which nobody would be fooled by Jacob Rees-Mogg.

It is partly the language: current affairs shows (with cameos from almost everyone; so much of John Humphrys, it is amazing he found time for his actual job) are preoccupied by the “snoopers’ charter”, a powerfully redolent term, casting you straight back to a pre-crash era when not much else was going on. Yet there are anachronisms: David/Dave, researching Hawes’s Julia Montague, lights on the fact that she voted for the Iraq war, which we understand immediately is both a trigger for him – those battlefields are where he got his PTSD – and significant for her, scoping out the reaches of her moral compromise. In 2006, where I put this show’s soul, the references to social media notwithstanding, it would have been completely unremarkable, and certainly not illuminating, that she voted for that war, since so did everyone else (yes, yes, except Jeremy Corbyn).

Hawes’s character is putatively modelled on Amber Rudd – it’s putative, but so open that she was game enough to write a column for the Times about her own bodyguards and whether or not she fancied them (well, sort of). But the era is far more suggestive of Theresa May’s time as home secretary, not because she is more like Montague, but simply because the waters in which Rudd swam are so different to these, everything so much more extreme.

So you are in an era that is a replica of the 00s, shot through with the buzzwords of now, the language and concerns of yesterday, spliced with the certainties of today. It makes you feel as though maybe you’ll be allowed back – maybe we’re not in a new world – or maybe there’s at least a portal, for an hour, on the telly.

There is nostalgia, too, to the storytelling, its pace electric, its twists so tight I audibly gasped pretty well all the way through the second episode, and yet, in retrospect, so signposted that I wondered whether I had deliberately avoided seeing them coming, in order not to ruin both the show and that elemental, pre-Netflix innocence – a time before complexity took over from suspense.

Hawes’s home secretary Julia Montague is modelled on Amber Rudd – but in the era of Theresa May’s holding the position. Photograph: Sophie Mutevelian/BBC/World Productions/Sophie Mutevelian

But sure, obviously nobody’s saying this isn’t also a sex thing. The erotic charge of the bodyguard as a character is a fixture of the psyche. To have skipped the obligatory scene where Madden saves Hawes’s life would have been professional negligence, and God, it worked: her covered in blood in the back of an armoured car, him summoning bravery beyond even the circumstances, to conquer the demons of his own that were worse. (Though, actually, the scene where he takes his shirt off because her mean assistant spills coffee on her and won’t surrender her own blouse because “it wouldn’t fit” is a much more elegant, Austen-esque moment.)

But – not unlike the Whitney Houston film, actually – it works because of the reversal of sexpectation: he may be protector, but only she can initiate (and does it classily: “I’m not the queen. You’re allowed to touch me”). Perhaps more key, for the gender studies class, is that she looks great, of course, but he is the sex object. He is the one the camera goes to, the one whose clothes it’s waiting for him to get out of. The cast is a roll call of female actors but this upended dynamic – who has agency and who is objectified? – is bigger.

So, anyway, that is why middle-aged women like it. It is actually more notable, viewing-figures wise, for pulling in the notoriously hard-to-reach 16- to 34-year-olds, for whom it was the first drama to approximate the popularity of Love Island and Bake Off. Those shows may turn out to have pulled screen culture into a bizarre reverse: audiences were reminded of the peculiar heart-swell that comes when everyone watches the same thing at the same time, the way the experience changes from one of atomised spectatorship to one of shared participation. But I don’t want to hand this, or indeed, anything to Bake Off: Bodyguard is its own alchemy.

• This article was amended on 7 September 2018. An earlier version referred to the Daily Mail. This has been corrected to the Mail on Sunday.