Hard as it may be to imagine anyone eclipsing the sex appeal of Ross Poldark by being darker, sexier and even better with horses, someone has. Yes, ladies of Great Britain, Rupert Campbell-Black has landed straight from the pages of Jilly Cooper’s 1988 bonkbuster Rivals on your screens here in 2024, and you are all in trouble. A lot of trouble.

Rupert gives the best riding britches and bronzed biceps since Aidan Turner was seen scything topless. He’s hot hot hot, joining the Mile High Club on Concorde and serving up a scorcher playing naked tennis in the sun. Even dressed as Santa come Christmas, he’s the gift that keeps on giving.

So hat tip here to Alex Hassell, whose swarthy looks and CV as a serious Royal Shakespeare Company actor (he was garlanded for his Henry V) don’t immediately suggest him to play a blond-haired, blue-eyed, tabloid headline-hogging love rat. ‘I was slightly concerned at first,’ says Jilly, ‘because my Rupert in the book is blond and blue-eyed, and Alex is very dark-eyed and olive-skinned. But he’s such a good actor.’

From the moment he strides out of the loo having had supersonic sex (he makes Mach 1 at the same time as the plane) with the Daily Scorpion journalist ghosting his memoirs, Alex Hassell owns RCB, as Jilly fans call him. ‘I always believe in laying one’s ghost,’ he sighs as he swaggers back down the aisle, and the millions of women who grew up fancying the rotter know they’re in safe hands.

So hat tip to Alex Hassell, whose swarthy looks and CV as a serious Shakespearean actor don’t immediately suggest him to play a blond-haired, blue-eyed, tabloid headline-hogging love rat

It wasn’t all plain sailing for Alex though. ‘Some days I’d be quite intimidated because the scene would describe Rupert walking into a room and everybody stops and looks at him and swoons,’ he says. ‘I was nervous about that, but everyone was told to act as if I was Harry Styles, and then my day turned into a wonderful day.’ So what does he think of Rupert? ‘While he is in many ways a s***, he’s not a bad man.’

Rivals is a riot and a romp, faithful to the book but with some sinuous updating to make what was the ultimate 80s tale of wealth, power and corporate backstabbing more nuanced. It is shagtastically good fun and if you’re old enough to have properly enjoyed the 80s, you’ll be drowning in nostalgia for those brash, optimistic champagne-fuelled years.

There are chaps in pinstripes and scarlet braces; women in power suits with root perms and earrings the size of a bin lid. Desk toys have an un-ironic place on boardroom tables and chintz runs amok in the English country house. Everyone is somewhere between slightly tight and completely plastered a lot of the time and can get up to mischief without being found out by their phone. The soundtrack alone will make you cry with longing.

‘We do it lovingly, but as the series goes on we address feminism, racism, sexuality, homophobia and snobbery,’ says showrunner Dominic Treadwell-Collins, who sees Jilly Cooper as a social commentator on a par with Austen or Dickens. ‘Rivals is a raucous party that gets darker. We keep our moments of joy, but the party gets a bit more warped.’

That’s not to say this new Disney+ eight-parter is any less fruity than the book. ‘If you had that copy you borrowed from your friend and it fell open at various pages – we’ve done all those bits,’ he acknowledges.

Emily Atack took to watching reruns of Top Of The Pops in which her own mother, the actress and singer Kate Robbins, appeared, by way of research

That classic Cooper sauce is still in there too. ‘How long do you spend on a cock?’ one guest asks Lady Monica Baddingham at a pheasant shoot. ‘Well, generally speaking, I can finish one off in 15 minutes or less, but my hands aren’t as quick as they used to be,’ she replies.

Or when TV technicians prep Rupert for his interview with TV journalist Declan O’Hara (played by Aidan Turner, yes, he of the topless scything). ‘The make-up artist is going to touch you up,’ they tell him. ‘I’d love her to,’ says RCB, ‘but I’m just about to appear on national television.’

There’s lashings of this since we are back in the (imagined) county of Rutshire, deep in the (real) Cotswolds, the setting for Jilly Cooper’s multi-million-selling Rutshire Chronicles series of novels. Riders, the first book, introduced Rupert as he chased Olympic showjumping gold. In Rivals, the second, Rutshire’s commercial TV station Corinium is up for franchise renewal and RCB is again at the heart of the action. ‘In bedroom and boardroom,’ promises Jilly, ‘the fight to capture the Cotswold Crown is on.’

Lord Tony Baddingham is Corinium’s boss. He’s on Concorde too, locking horns with Rupert, now a rising star in the Thatcher government, two of the ‘rivals’ of the title. He is played, with just the right amount of aristo-executive villainy, by David Tennant, persuaded to take the role by his wife, Georgia, also an actor and a huge Jilly Cooper fan.

Lord Tony Baddingham is played, with just the right amount of aristo-executive villainy, by David Tennant, persuaded to take the role by his wife, Georgia, a huge Jilly Cooper fan

‘I had my research fellow, who I live with, who could tell me anything I needed to know,’ laughs David, adding his casting caused a frisson at the school gate. ‘It’s a certain generation of women who go a bit giddy at the thought this has become a TV show. I just hope we can meet everybody’s fantasies…’

Well, if those fantasies include seeing Aidan Turner’s bare bottom you can tick that one off the list though he is, unusually for Rutshire, bedding his own wife at the time, rather than someone else’s. Declan O’Hara is Lord Baddingham’s star hire, married to fiery Maud, a man-hungry former actress.

Maud is played by Victoria Smurfit who really, really wanted the role and went full ‘Rutshire’ to get it. ‘I made this big decision where I thought, “Go big or go home.” It was December: freezing cold, ice on the ground, snow coming down through London. And when I arrived at the audition space, I had my coat on, and I walked in to meet the team who were in hats and gloves because it was even cold in the studio. I said, “Hello, I am Maud. You’re all dressed for London in December and – I threw my coat off and had this flimsy dress on underneath – I’m dressed for summer in the Cotswolds, darling!” Going home was quite chilly, I’m not going to lie, but it was worth it.’

Maud is played by Victoria Smurfit who really, really wanted the role and went full ‘Rutshire’ to get it

In Rivals she specialises in making an entrance: do enjoy the scene with the camel.

As for Aidan Turner, with an absolute whopper of a moustache, Day-Glo yellow socks and a battered old Mini Cooper, he’s more workaholic dad than sex god. ‘That car, it’s got four gears but only three work,’ he groans. ‘The floor has holes in it. I think we maxed at 42mph. It was like driving a go-kart.’

Like all the actors, he knows his Mini isn’t the only bit of Rivals that could have looked clapped out in 2024, if not for the clever screenwriting. ‘I think we’re saying, “These are examples of the problematic behaviour that was acceptable at the time,”’ he reflects. ‘Some of it still does exist, but a lot has changed. It’s interesting to watch a show like ours and think, “We’re still doing that, maybe we should have left it in the 80s.”’

That said, ‘people having sex’, as David Tennant gleefully points out, ‘is timeless’ and all the characters are still aboard a classic Jilly Cooper sexual carousel. Baddingham is having an affair with his brilliant American TV producer Cameron Cook (now a black character), and Rupert is fending off Maud while falling in love with the eldest O’Hara daughter Taggie (played by Sex Education’s Bella Maclean), who’s only 20.

As for Aidan Turner, with an absolute whopper of a moustache, Day-Glo yellow socks and a battered old Mini Cooper, he’s more workaholic dad than sex god

Electronics mogul Freddie Jones (Danny Dyer) and his wife Valerie are the nouveau riche trying to crampon their way up to social acceptance, but Freddie has feelings for novelist Lizzie, whose husband is Corinium’s ghastly news anchor James Vereker. Then there’s disgraced deputy PM Paul Stratton, newly married to his mistress Sarah (Emily Atack), who we first meet playing naked tennis with Rupert.

It’s a legendary Rivals scene (inspired by the tennis court at Jilly’s own house in the Cotswolds) where the tennis ball isn’t the only thing bouncing over the net. ‘The tennis scene was probably one of my favourites,’ says Emily. ‘It was a beautiful sunny day and I’d been exercising, I’d been – I wouldn’t say dieting, I love wine and pasta too much – but I’d been doing my sit-ups and my squats, and I was ready to do this naked scene!’

So it really is Love All, even among Rutshire’s lusty teenagers, for whom ‘I’ve got some Malibu upstairs’ is still a winning pick-up line. And this only takes us to the mid-point of the series: there are four further episodes and a lot more bed-hopping and dastardly boardroom behaviour to come.

It’s hard to overstate the scale, complexity and gleaming polish of the show, with its ensemble cast and Cotswold locations crammed with pale gold mansions, buttercups, bluebells and red phone boxes. (You might recognise 16th-century Chavenage House near Tetbury, which becomes the O’Haras’ home, The Priory, because that too was in Poldark.) There are sweaty horses, bounding hounds and huntsmen in their pinks.

You might recognise 16th-century Chavenage House near Tetbury, which becomes the O’Haras’ home, The Priory, because that too was in Poldark

Dinner parties start with pheasant and finish with pavlova, and guests disco dance until it’s time for a Survivors Breakfast. Picnics are enjoyed out the back of a Land Rover – green, what else – and Rupert Campbell-Black is secretly so lonely he shares his bath with his favourite black Labrador, Beaver.

The original book was 720 pages long and they’ve done it proud. Some days, according to Alex Hassell, there were 42 main characters on set at the same time, making it, he thinks, the biggest film unit in Europe.

Vintage Ungaro and Laura Ashley were sourced for the women, 80s-style suits handmade for the men. A safe had to be brought in to stash the 80s watches which are now worth an eye-watering amount. Someone’s mum knitted a bunch of pre-divorce Diana jumpers, Nafessa Williams, who plays Cameron Cook, modelled her ponytail on Sade’s and Danny Dyer drew on his own experience of snobbery as he, a working-class untrained actor, fought to break into theatre.

Emily Atack took to watching reruns of Top Of The Pops in which her own mother, the actress and singer Kate Robbins, appeared, by way of research. Everyone is wearing Wayfarers. Cadbury’s Fruit And Nut still comes in paper and gold foil while Wham!, Roxy Music, ABC and The Communards are on the radio. You can virtually smell the Elnett extra strong hold hairspray, the Drakkar Noir aftershave and the garlic chicken vol au vents warming through in an Aga somewhere.

Like the rest of the cast, Nafessa Williams knew what she was getting into with her sex scenes (Cameron has relationships with first Lord Baddingham and then Rupert). ‘I mean, we all knew what we were coming to do, so there were no surprises. I think it’s a matter of making sure you’re comfortable with each other and you’re listening and asking questions: is it OK to do this? Is it not OK to do that? It is a dance, so you essentially have to practise that dance before going on the dance floor.’

Like the rest of the cast, Nafessa Williams knew what she was getting into with her sex scenes

Plus, because Rivals is a bonkbuster – a label which has both supporters and critics among the cast – there was safety in numbers, as Emily Atack explains. ‘When we were doing all these scenes, we flocked to each other to talk about it, and support each other and really big each other up and we laughed about it. They were such a huge part of our bonding as a cast and as friends. It really interested me to see what nudity does to human beings – we were all like giggling teenagers, hugging each other, high-fiving each other, going, “Oh my God! Yes! You did it!”’

That said, they were all rigorously policed by not one but two intimacy co-ordinators, something which would not have happened had Rivals been turned into telly closer to the time the book came out. The intimacy team placed a partially deflated fitness ball between some of the actors so they could rock and create rhythm while having a physical barrier. Others were encouraged to use a tap-in tap-out psychological technique, clapping their hands before a take to signal to themselves they were in character, and then clapping at the call of ‘Cut’ to signal they’re themselves again. ‘We’ve been equal opportunities with sex,’ says Dominic Treadwell-Collins. ‘You will see an awful lot of willies.’

It was the only way to film the lovely, unbridled sort of sex synonymous with Jilly Cooper and the author, now a venerable 87 years old, is characteristically relaxed and happy about the outcome. ‘I trusted Dominic like mad,’ she says, ‘I knew it would be all right!’

A superstar writer since the 60s, made a DBE for services to literature and charity in this year’s New Year Honours, she wasn’t at all bothered when one of the actors, Lara Peake who plays Corinium PA Daysee, failed to recognise her at a read-through. ‘She came over and said, “Oh, you’re the lovely Daysee,”’ Lara recalls. ‘I said, “Yeah, I’m so excited. Who are you playing?” She was like, “No, darling, I’m Jilly…”’

‘Rivals is my favourite novel,’ confirms the author ahead of the series dropping later this month, ‘because I love the characters so much. Even the most ruthless display moments of vulnerability and the shyest show courage and integrity as true love blossoms.’

But can you believe it, RCB almost wasn’t in the book. ‘Originally, I intended to leave out Rupert, my hellraising hero, because in Riders he was cruel both to women and his horses,’ says Jilly. ‘But I missed his glamour and humour.’ She belatedly wrote him back in as a lead, reinforcing his place as one of the most lustworthy men in British fiction.

She says she loves the ‘ruthless glamour’ Alex Hassell brings to her creation, while admiring the greater vulnerability and tenderness the Rivals writers’ room has imagined for RCB today.

His casting has been the subject of heated debate everywhere from Mumsnet to The Tack Room, the online chat area of Horse & Hound. The actor almost withdrew from the first audition because he couldn’t see himself making everyone swoon but, by golly!, to borrow a Jilly Cooperism, he does. So much so he was sad when the shoot was over. ‘No one was looking at me like I’m the most sexy man on the planet any more,’ he says. ‘It was tough.’

Anyway, if you’d like to watch him make your screen melt, are old enough to remember the 80s, or young enough to think it must have been cool to be there, then clear eight hours in your diary because you won’t be able to stop watching Rivals.

But start early or you’ll be late to bed, and that would never do, not in Jilly Cooper’s world.

• All episodes of Rivals are exclusively on Disney+ from 18 October.