Georgian England in the 1760s, and another girl is being auctioned off to the highest – and highest-wigged – bidder. Not by a bawd in the brothels of Soho, but by a father in the bucolic countryside where his daughter Catherine – “a headstrong girl” who “with firm instruction shall transform into a biddable and doting wife” – has captured the interest of a potential husband. But where is she? In the stables. Horse-mad, that one. Which, in saucy period-drama speak, means she’s … rwell, you can guess.

'Obscenely enjoyable': why Harlots is the best show you're not watching Read more

In Harlots, which gamely ruts on for a third series on Starzplay despite its ruinous reputation as the finest show no one is tuning into, this will end not just badly but in Bedlam. The next time we see Catherine she’s in the madhouse, and perhaps worse, in the bed next to Lydia Quigley. Vanquished in the finale of season two, gentrified London’s high priestess of bawds is now powerless, wigless, tortured daily under the guise of modern medicine, and still trying to groom any girl unfortunate enough to come into contact with her. She continues to be played with the most deliciously monstrous histrionics by Lesley Manville. This is not so much chewing the scenery as gorging on it. “His rod will be his ruin,” she spits of the doctor treating Catherine’s “condition” by raping her. “It always is in the end.”

Elsewhere, Charlotte Wells (Jessica Brown Findlay), daughter of Greek Street bawd Margaret (Samantha Morton) who we last saw being sent to America in chains, has set up her own house – the ultimate aim for prostitutes at a time when one in five women in London works in the sex trade and the only alternative is marriage, which often amounts to a similar servitude. This means fewer men in her bed or, in Harlots slang, bartering more money than cunnie. Lady Isabella Fitzwilliam (Liv Tyler) has decided to own the scandal that threatened to destroy her. She bursts into a gentlemen’s club where lords gamble and entertain courtesans in plain sight and announces, in her best breathless-portentous voice: “I have a daughter born out of wedlock and her love is my greatest blessing. Neither she nor I will bow our heads to your censure.” Huzzah!

Facebook Twitter Pinterest Gorging on the scenery … Liv Tyler. Photograph: Ollie Upton/Starzplay

Not unlike this review, the tone of Harlots continues to be … disconcerting. One minute a rape, the next a fruity challenge thrown down by Lucy Wells, London’s most coveted harlot, for buffoonish culls to chase her around Soho. “Whoever licks that bald man’s head first gets me!” she laughs through gritted teeth. There is a jarring clash between the grim subject matter and the relentlessly ribald sew-pearls-in-your-muff-hair tone. But at its best the discomfort is the point. Sex work is a brutal and messy business. What saves Harlots from falling down the ancient traps of objectification, fetishisation, and sexist tropes of “tarts with hearts” and hookers who secretly love it is its solidly female gaze. Plus its commitment to diversity and top-notch writing. This is a series created, directed and written by women. The bawds are not merciless. Not everyone is white. The men paying for sex are not kind. And the sex is not sexy.

Golden Square, the prestigious address out of which Lydia Quigley trafficked her “princesses” to lords and justices, is now in the hands of a cartoonish mother-and-son power couple from Bristol, Elizabeth and Fredo Harper, who intend to run it as a molly house (a brothel for men seeking sex with men). “How does it pay?” asks Lucy Wells, who has a share in Golden Square. “It’s a hanging offence,” Fredo replies with Fleabaggish knowingness, “so double.” For the first time in Harlots, men are more central to the plot and a new threat is provided by brothers Isaac and Hal Pincher, determined to become Soho’s richest pimps. Isaac, played with not nearly enough menace by Alfie Allen, implausibly gets under Charlotte’s skin, taking a cut of her girls’ earnings and setting fire to her house. The turf war is on and for once it’s not between women. This is welcome, but I still preferred it when the men in Harlots were little more than cockstands.