Even if you’ve not watched the show, you’re likely to know that Bridgerton is filled with steamy scenes of lords and ladies, dukes and duchesses locked in passionate embraces. The third season, set in 1815, is as sexy as ever … for some.

One of this season’s major side plots is the Featherington family’s need for a male heir. With both Prudence (Bessie Carter) and Philippa (Harriet Cains) now married, Lady Featherington (Polly Walker) is desperate for one of her daughters to produce an heir and inherit the family estate. And time is of the essence. With questions arising over the authenticity of the inheritance document, the girls need to get to work before Lady Featherington’s schemes are uncovered.

Not one for patience, Lady Featherington regularly checks in with the girls about their pursuits and is quickly convinced they haven’t been “engaging in the, eh, necessary … activities”. She pursues the topic further and learns of Prudence’s dislike for the act of being “familiar with each other,” as it flattens her hair.

More shocking, however, is that it seems Philippa is entirely ignorant of how to have sex.

“Inserts himself? Inserts himself where?” she asks. Philippa explains that when she and Mr Finch lay together they kiss, he makes an odd sound and goes to change his breeches. Despite being married to Mr Finch for a year, the pair have still not had intercourse.

But how could this happen? How could Mr and Mrs Finch be so naive? Not knowing how babies are made has been a thread in Bridgerton since the first season. A woefully unprepared Daphne Bridgerton (Phoebe Dynevor) entered into marriage with Simon Basset (Regé-Jean Page), the Duke of Hastings, and felt betrayed when she found out that he had been withholding his “seed” and denying her a child.

This season, Philippa’s lack of knowledge makes for a comedic series of misunderstandings, but this scenario and level of ignorance was not as common as Bridgerton makes it out to be.

Mr Finch certainly would have known about the birds and the bees so his lack of action, given the demand for an heir, is rather astonishing. He, like the majority of elite men of the time, would have learned of such things – sex, how to please a woman, and even how to masturbate – from a host of sources including older family members and first-hand experience.

Earlier in the 18th century, two fathers – the politician Lord Chesterfield and the French philosopher, Denis Diderot – were educating their respective son and daughter. Both fathers were eager to ensure their children were properly educated before reaching the marital bed and employed various methods to achieve it.

Lord Chesterfield, whose chosen form of education was via correspondence, wrote his son over 300 letters to instruct him on all matters of life, including business, politics and pleasure. Chesterfield instructed his son to gain sexual experience, preferably “with a refined Parisian lady rather than with a streetwalker,” not unlike Anthony Bridgerton’s (Jonathan Bailey) experiences in season one with an opera singer or Colin Bridgerton’s (Luke Newton) exploits abroad before the start of season three.

Denis Diderot was, it must be said, pretty progressive, as it was uncommon for fathers to be involved in the sexual education of their daughters. In an effort to enlighten his daughter, Diderot arranged anatomy lessons for her with a famed wax-worker, Mademoiselle Biheron.

Through these lessons Diderot’s daughter became familiar with the various parts of the male and female body, their functions, and how they worked in relation to each other. Diderot believed this to be essential learning and offered the Mayor of London, John Wilkes, the same opportunity for his daughter when Biheron visited London. Wilkes declined.

Philippa’s lack of knowledge, while more understandable, is also highly implausible. Most girls, even those of the fashionable ton, would have encountered enough knowledge “to penetrate the mysteries of love” before they hit puberty.

There were many books at hand. Aristotle’s Master-Piece (1684), a sex manual that doubled as a practical engagement gift, and Nicolas Venette’s Mysteries of Conjugal Love (1712) were as instructive as they were explicit. Jane Sharp’s reprinted edition of The Midwives Book (1671) was equally informative, and though outdated, was still very much in print and circulation.

Other genres of literature, from fiction to botany, also held revealing details in their pages. John Cleland’s erotic novel Fanny Hill: Or, Memoirs of a Woman of Pleasure (1749) though banned almost immediately, found its way into hundreds of hands. The book follows Fanny Hill as she enters the world of sex work and learns from the women around her about a vast range of experiences, preferences, and positions. Readers, in turn, learned a lot from Fanny Hill.

Even if Philippa overlooked Aristotle’s Master-Piece, Fanny Hill or other literature, sex was hiding in plain sight throughout the Regency world. Descriptive knowledge often came from other girls, family, or servants, while animals, satirical prints and people caught in the act were all visual sources of education.

Thomas Rowlandson’s graphic engravings often combined humour, politics and erotica and were openly displayed in the streets while indiscreet couples where known to fornicate on Westminster Bridge and in St James’s Park. Surely Mrs Finch might have learned a thing or two from the city whirling around her?