Harlots has a huge and magnificent cast, intricate and labyrinthine plots involving ingenious backstabbing on a grand scale, and it has even developed its own brilliantly lewd lexicon. Yet the most confusing thing about it is why, after two outrageously camp and emotionally powerful seasons, it isn’t a TV phenomenon yet. As its third season arrives on Hulu (and Starzplay, via Amazon Prime, in the UK), perhaps it will finally start to earn its keep, like a down-on-her-luck gal in need of an honest income.

Set on the grimy but decadent streets of mid-1700s London, Harlots tells the story of courtesans of every social standing, as rival brothels and battling “bawds” compete not just to stay on top, but to stay alive. The first two seasons pitted the monstrous madame Lydia Quigley, a woman at the top of her game, not so much lacking in morals as violently opposed to them, against the more homely Margaret Wells, whose down-to-earth brothel was on the rise. Watching Lesley Manville and Samantha Morton spit insults at each other was a true wonder, but it was a battle built on shaky ground, and a whole lot of history. Its sympathies are more subtle than its brash gaudiness initially lets on. The line between good and evil may appear clearly drawn – Mrs Quigley sends girls to their deaths for money and to make inroads with the aristocracy whose business she needs to survive, but really, is she so very different to Margaret, who sold her own daughters’ virginities to the highest bidders, and will throw her own girls to the lions if it means she will come out on top? And then it turns again – Margaret was teaching them survival in a world where their options were so limited as to be non-existent. Nobody is covered in glory, but there is sport-like fun to be had in getting behind your side.

Given the level of titillation that Game of Thrones tried to to whip up every time it went near a brothel, the sex in this show feels quietly revolutionary. As you would expect, Harlots is full of sex, though not so much nudity, because most of the action is the pull-up-your-skirt kind (according to the creators, this was a practical detail, rooted in history – it was too cold to keep all those layers off for long). Some of the sex is enjoyable. Most of it is simply a means to an end, a play for power, on a vast scale of potential returns. Many of the women find pleasure on their own terms, when they choose to. It is a show created by women, and it shows. The female gaze is the only gaze.

Its women have brief, thrilling victories, but this isn’t naive enough to turn 18th-century London into a fairytale world in which women have the upper hand. They remain the property of men and even those with money know it is not their own. Lady Isabella Fitzgerald (Liv Tyler), who brings her wealthy sympathies to the troubles and beds of the courtesans, has to wile and scheme to exist outside of her evil brother’s control. Wealth and social standing are everything, and watching women’s stories turn on the advantage or otherwise of the class they were born into is no less relevant because this is set 300 years ago.

Lesley Manville in Harlots. Photograph: Liam Daniel/Hulu

More than anything, though, this is almost obscenely enjoyable. Its language, a mix of genuine 18th-century slang with a little modern embellishment, is lewd, creative and bright. Those who found joy in the ridiculous antics of The Favourite, set 50 years earlier – the duck-racing, the food fights – will find revelry of a similar hue. The makeup is bold, the outfits outlandish and the hedonism overt. I love a slow, pretentious drama as much as any TV nerd, but Harlots delights in its breakneck pace. In this world, people die young and sentiment is hard to come by, so it makes sense that it simply moves through the action at a giddy speed. People make alliances and break them. They move from one house of ill repute to another, often forging friendships that are more useful than genuine. Schemes flourish and crumble, deception is rife and everyone has something to hide. If it has a surprisingly delicate touch when it comes to sex, class and women’s status, it is robust in its dedication to rolling up its sleeves and getting on with it. More happens in a single episode of Harlots than in a whole season of, say, Big Little Lies.

Harlots returns for its third season with a dilemma. It wrapped up, with relative neatness, the Quigley-Wells standoff, and made Maggie’s daughters Charlotte and Lucy the new over-ladies of London’s sex-for-sale scene. There were so many twists in the first two seasons that it was hard to see where it might go next, when every possible combination appeared to have been exhausted. But on the basis of its first three episodes, the ante has been upped. There are new villains in town, violent men who think they can take Charlotte’s “We’ll do business as we always have, with bawds at the helm” philosophy away from her by brute force. Lydia Quigley is finding a way to rise out of Bedlam and attempt to retake her crown. And there is a moment in the third episode so shocking that I genuinely clasped my hand to my mouth. In a world of arson, hangings, incest, bare-knuckle boxing, molly houses and murderous cults, the fact that Harlots still manages to keep its viewers on their toes is a true testament to its greatness. It’s about time it got the audience it deserved.