Diarmuid Breatnach
Most modern criminal detectives have sex – I know this from reading, thankfully not from personal experience.
The older set, Holmes, Inspector Maigret, Nero Wolfe, Miss Marple – they didn’t. Holmes was into a barely-concealed opium habit and Wolfe had an obsession with orchids; Poirot was obsessive-compulsive and probably fetish-obsessed with his patent-leather shoes. Miss Marple, who first appeared in a novel published in 1930, reflected her times even when the times passed her (Nemesis was published as late as 1971) and as to a suggestion of sex: “Good God! What kind of a degenerate are you? A woman detective having sex? And a pensioner?”
In modern times we might reflect that “of course there was her live-in maid … and that succession of young women she trained as maids ….”
Not only did they not have sex on paper, they were all single except for Maigret, so there was an absence of potential sexual activity to distract one. Maigret of course was French so like many middle-class men of his time would have had not only a wife but a mistress too but …. we don’t talk about that.
Yet sex is one of the most basic driving instincts – it governs procreation of species and, working in tandem with natural selection, rules on evolution of all species. How come it was left out?
The characters reflect their times and their class, of course, as well as what was expected of their class, sometimes with a little added taste of the unexpected – but not in sex. Yes, we know that DH Lawrence’s sexually-explicity (and trans-class) Lady Chatterly’s Lover was published two years before Agatha Christie Miss Marple’s first appearance in a novel, in Murder at the Vicarage (1930) – but Lawrence was published in Italy. Sniff! — those Continentals! A year later Chatterly was published again in France and – interestingly – in Australia. But all that publishing was done privately. In 1960, when an unexpurgated edition was finally published in the “United Kingdom”1, Penguin, the publishers, were subjected to a famous obscenity trial but, when they won, sold three million copies. It was still banned in the Irish State, of course but we weren’t alone – the USA, Canada, Australia, India and Japan all banned it too.
Romantic and gothic novels of the time didn’t have sex either, except in the mention of a child born out of wedlock, though the suggestion of or even history of rape was there at times. Sexual feelings of the heroine (and sometimes of the hero) were conveyed through descriptions of a blushing cheek, longing looks, palpitating heart and breast (but no mention of nipples!), feeling faint in the head …. all above-board and more importantly, all above the waist (though still allowing the reader’s imagination to eroticise, of course).
The most important point to grasp here I think is that something being published does not necessarily reflect the dominant social mores – it is its acceptance by society and its popularity that tells us most. There has always been material around that transgressed socially-dominant sexual standards but those standards were still dominant – and the material may even have worked as a pressure-release valve, as for example with the huge numbers of sex-workers, female and male, that walked the streets or entertained in special houses in sexually-repressed Victorian Britain, particularly in London.
The 1960s brought about a huge jump in tolerance of explicit sexuality, partly fueled by a decade of expanding consumerism and a push for more of the same and partly by the rise of the youth and student movement and its challenge to hierarchical values and control.
THE NEW DETECTIVES
But for decades already, the new criminal detectives had arrived – or at least their advance skirmishers. One of the most influential, beating the later pack of the 1960s by a good three decades, Dashiel Hammett was hugely influential with the creation of what became known as the “hard-boiled” genre of detective stories and also in the “talking detective” style, in which the central character is also the narrator.
Hammett, a left-wing activist who got blacklisted as well as a popular crime fiction writer, had been employed by the Pinkerton Detective Agency2 and wrote many published stories but only five novels, all between 1929 and 1934 (even though he lived to 1961): Red Harvest, The Dain Curse, The Maltese Falcon, The Glass Key and the The Thin Man3.

(Source: Internet)
Raymond Chandler, who acknowledged his debt to Hammett, had The Big Sleep published in 1939, based on a couple of short stories (he’d been writing those for decades). He banged them out pretty regularly after that: Farewell My Lovely (1940), The High Window (1941), The Lady in the Lake (1942); then a break until The Little Sister (1949), another gap until The Long Goodbye (1953) and Playback in 1958, a year before he died.4 at the age of 71.

(Source: Internet)
The gap in the 1940s is easily explained by the film scripts for Double Indemnity along with And Now Tomorrow (both 1944), The Unseen (1945), The Blue Dahlia (1946). Strangers On A Train was produced in 1951.
James M. Cain (1892-1977) published The Postman Always Rings Twice in 1934 and, as well as short stories, another fourteen novels during his lifetime. Among those was Double Indemnity which, like Postman etc, was made into a film.
Mickey Spillane published his first novel, I, the Jury in 1947 and went on to publish another twelve before he died in 20065.

(Source: Internet)
The new private detectives novels between the 1920s and the 1960s introduced detectives who had or were tempted by hetero sex but, however graphically the allure might be described, the sex was never described in detail. These novels also featured the femme fatale, the attractive and sexy woman who was also dangerous – capable of murder and treacherous. The detective was more likely to have the sex-interest woman jailed or even killed, or walk out on her, than claim her as the prize. And yes, the detectives in this genre were all male.
These novels featured violence – not just the violence to the homicide victim but regular knockouts with a pistol butt across the head, graphic physical fights with fists and feet (and even teeth!), shootouts … the detective characters not only suffered violence but engaged in it too (particularly Mickey Spillane’s Mike Hammer).
During the 1940s and ’50s the novels were paperbacks, low-priced, produced on cheap paper to a size that could fit into a man’s jacket or coat pocket (and some handbags or, in the USA, “purses”). This form of private detective and some other kind of publishing came to be called “pulp fiction”, from cheap magazines of short stories, i.e destined to be turned back into paper pulp soon after reading).6
The covers (or “jackets”) of “pulp fiction” novels were often lurid, portraying violence and heterosexual sex. Women dressed in revealing deshabille, often with seductive expression and posture, tended to share the cover with a “hunky” type of man, with a gun visible in the hand of either. Sometimes a dead body, male or female, lay on the ground too.
This kind of writing was baptised “Noir”, i.e “black”, mainly reflecting the dark sides of the detective’s character and especially of his clients and of surrounding society, cynical, corrupt, characters often morally-flawed, doomed, dogged by ill-luck and bad choices.7 Production in film of that writing came to be called “film noir”, the content reflected in low-light shots in black & white filming, which later transferred (with some difficulty) even to colour film. But still, the sex was never graphic in the writing and was more pruriently hinted at than witnessed by the reader.

The writing could be elegant in descriptions and it could also be tight; dialogue was very important, with the detective and his adversaries dueling in verbal repartee, which the detective usually won in the verbal category but for which he often paid physically.
Of course, some cities in the United States had seen a lot of violence in reality, in particular during the ill-fated years of alcohol Prohibition (1920-1933) and the attendant rise of crime syndicates seeded in the working class immigrant communities of Irish, Jews, Italians, Sicilians …. Reading about such events as arrests, trials and mobster shoot-outs in newspaper reports provided also an audience for the material in the form of short stories, novels and later films. That audience grew during the succeeding decades and is still a wide one today, with a diversification of sub-genres and detectives in countries other than the USA or Britain, usually also in translation from their native languages.
But … back to sex and the detective. As the years rolled on past the 1960s towards the end of that millennium, the sexual activity of the private detectives became not only implicit but often explicit (with the possible exception of the Nordic detective novels). And we now had some female protagonists too: police detectives, uniformed police officers, private detectives and forensic pathologists. And if none of the main characters were ever gay, lesbian, transgender or transvestite, such characters did appear, usually treated more gently than in the past and at times actual second-line “good guy” actors in the stories.
It appeared that all previous sexual taboos in the detective story – all legal ones at any rate – had been broken.
Well, not all. Not masturbation.
Not even modern private detectives masturbate. Which is truly remarkable, when one considers, according to all research, how common that activity is in the non-detective population.
End.
REFERENCES & SOURCES:
For dates of authors’ birth and deaths, also of bibliography, Wikipedia entries on the authors.
Also: https://en.wikipedia.org/wiki/Pulp_magazine
Other:
Particularly for the footnote on Rebel Frontier: https://subjectguides.library.american.edu/dashiellhammett
FOOTNOTES
1I somehow doubt it would have got far in the Six Counties (“Northern Ireland”)
2 See Rebel frontier [electronic resource (video)] : organized labor vs. the Anaconda Copper Company / Network Ireland Television. New York, N.Y. : Films Media Group, [2006], c2004.1 streaming video file (66 min.) : Martin Sheen – impersonating the voice of author Dashiell Hammett – narrates this compelling docudrama on immigrant labor and anti-war politics in 1917. As a young employee of the Pinkerton Detective Agency, Hammett spied for the Anaconda Copper Mining Company in Butte, Montana, during the height of labour struggles there. AU STREAMING MEDIA http://digital.films.com/PortalViewVideo.aspx?xtid=35494.
3 The Maltese Falcon, The Glass Key and the The Thin Man were made into films.
4All based on earlier short stories, except the last, which was based on an unpublished screenplay.
5A number of others, based on previously-unpublished material or short stories, were published posthumously.
6Even after the pulp fiction heyday ended in the 1950s, paperback novels are still being produced in roughly the same size, albeit with somewhat better quality paper pages and covers.
7“Noir” also came to be a literary descriptive term and is often used to describe a certain kind of writing today.