As the nation watches glossy costumes dramas, corset sales are on the rise, even though they’re locked down. Even in the 18th century, cantilevered looks could have been dangerous.

Is cleavage ever a plot device? The Russian court of the 18th century, as depicted in The Great (a hilarious new satire from Hulu & Channel 4), is a hotbed for moral iniquity and vodka. It is, however, about breasts as with most costume dramas.

Lady Svenska is a courtier who wants to get rid of Catherine the Great. Her decolletage shows that she is a baddie, long before she called Catherine “a bitch” because she refused to eat biscuits. There’s Georgina Dymov who is Catherine’s mistress. The gold-plated pendant pointed directly at her bosom reveals her libidinal desires.

Emma Fryer, the show’s costume designer says that “Georgina Dymov’s character makes it seem odd to have Georgina more covered up.” The show’s language is that the moral worth and virtue of female nobility are measured in the bust. Catherine even gives up her high necklines to have sex with her boyfriend.

The Great airs on Sunday nights. The opening credits include a disclaimer stating that the program is “based on historical facts, sorta”. It has been called “anti-historical.” It is about the marriage of the Russian-born princess Catherine, who was born in Prussia, and Peter III, which ended in a tragic end.

It can borrow from history, but it cannot ignore the facts. Contemporary fashion favors the cantilevered look. Women were judged on how much cleavage they displayed, depending on age and social currency.

A certain level of cleavage was considered fashionable in the late 18th and 19th centuries, says Susanna Cordner, a fashion historian who worked on the V&.A’s .Undressed: A Brief History of Underwear. She says that breasts were often ridiculed in the media and popular culture.

An overt cleavage was often viewed as a sign of “coquettishness, feigned youth” This is evident in cartoons by George Cruikshank and James Gillray, who used the bosom of a woman as “shorthand” for impractical vanity or fake innocence. Age was a factor too: Cordner states that “sometimes these commentaries [presented] the wearing of potentially revealing clothes, especially by older women as being poor taste.”

Fryer believed that the main focus should be on character, not cleavage. Fryer says that while it is not historical correct, de-robing was seen to add a sense debauchery and chaos to the background. His research was based on mid-Georgian portraits from the National Gallery, Givenchy, and Dior.

In Bridgerton, the Netflix series that introduces us to the high-class young “bon tons” of 1813 London, breasts are equally prominent. Bridgerton, which is set 50 years ago and many miles away from Peter (and Catherine), Russia, leans more on fiction and titillation than it does on fact and etiquette. However, Bridgerton’s London environment – Bath with its CGI carriages – subtle class lines are drawn around the neck.

You’ll most likely have them displayed if you’re a Featherington social climber. Lady Danbury, the wily dowager They are also there. If you are a Bridgerton of higher class, you will hide yours behind a marabou fan. Bridgerton’s costume designer, Ellen Mirojnick, describes this Regency cleavage as “mounds” that “mimic the cheek” and as such, treats them like props from a fever dream.

Viewers were not unimpressed by any of it. Some people asked how large chested women coped on Twitter. Some wondered if the breasts of some women were real. A 2,000-word article in the Smithsonian magazine queried their veracity altogether: “Corsets and stays of the Regency period were designed less to create the cleavage that modern audiences find attractive and more to lift up and separate the breasts like ‘two round globes’.” If they had used Regency style corsets, continued dress historian, Hilary Davidson, “you would have had boobs for days”.

According to these series, the stratified worlds of 18th century Russia and Regency England overlapped in class and imperialism just as much as they did in fashion. Cordner says that cleavage was more a result of wearing a corset than an actual focus. They were boned and stopped at the diaphragm. They were designed to support the bust and give rise to the regency “shelf”.

Fryer took care to get rid of the frills and frippery that 18th-century Russian necklines had. This was partially subconscious. “We wanted to blend historical drama with contemporary wear.” Keen viewers of Bridgerton will have noted that younger characters, or those with less social currency, tended to wear a pelisse (a jacket) or chemisette, otherwise known as a false front. These fronts can be removed and cleaned, much like Ganni’s “Zoom” collars. They are removable pieces that add style to a plain top. According to eBay, corset sales have increased by almost 50% since the shows aired.

These period dramas do not make for great documentaries. They are primarily about charismatic women who act as conduits to discuss current-day issues of sex, class and sexuality. It’s only a matter of time before we can prove otherwise.