The coincidence of two great film-makers dying in the space of three days would be striking enough. But Nicolas Roeg, the British cinematographer turned director who died on Friday aged 90, and Bernardo Bertolucci, whose death at the age of 77 was announced on Monday, had more in common than the time of their passing. Their reputations were forged at the forefront of a new kind of transgressive cinema in the 1960s and 70s, in which explicit depictions of sex and desire were a driving dramatic force, rather than X-rated window dressing. Sex in these films isn’t gratuitous titillation but a way of expressing character, motivation and meaning. Remove the beast with two backs from Roeg’s extraordinary early work – including Don’t Look Now, The Man Who Fell to Earth and Bad Timing – and it would be akin to tearing out entire pages from the scripts of more conventional movies. Expunge the sex scenes from Bertolucci’s Last Tango in Paris and one is left with a short film about flat-hunting.

The advances made and taboos busted set out a cinematic landscape we now take for granted

“Words have the tiniest importance,” Roeg said in 2011. “One moment of truth in a film can be seen instantly … All the subtleties in a poem, all the things you put in the rhythm of words, can be destroyed in one look.” The proof is on screen. There is no way to make rational sense of the merging of identities and the erosion of sexual boundaries between a gangster (James Fox) and a pop star (Mick Jagger) in Performance, except through the penetrating closeups and cuts with which their relationship is shaped by Roeg and co-director Donald Cammell. The clawing, rapacious passion between a widower (Marlon Brando) and a young stranger (Maria Schneider) in Last Tango in Paris, or an opera singer (Jill Clayburgh) and the junkie son (Matthew Barry) for whom she harbours incestuous desires in La Luna, resides in the unfettered physicality that was possible in the newly exploratory climate these film-makers helped to create.

Mick Jagger and Michele Breton in Performance by Donald Cammell and Nicolas Roeg. Photograph: Allstar/Goodtimes

The advances made and taboos busted by Roeg, Bertolucci and contemporaries such as Walerian Borowczyk and Nagisa Oshima set out a cinematic landscape we now take for granted when we watch the work of Catherine Breillat, Claire Denis, Pedro Almodóvar or Lars von Trier. Both men had served their apprenticeships at the feet of other great directors. Roeg began as a teaboy and worked his way up (second unit on Lawrence of Arabia, director of photography on Fahrenheit 451 and Far from the Madding Crowd); Bertolucci was an assistant director on Pasolini’s 1961 debut Accattone (which he notoriously said was “like being present at the birth of cinema”).

They were in thrall to French cinema. Bertolucci was a passionate devotee of Godard, most obviously seen in his third film, the incendiary Partner (1968), and Roeg an admirer of Alain Resnais, especially Last Year at Marienbad, itself an unexploded bomb of suppressed eroticism with which a connection can be drawn to Bad Timing almost 20 years later.

Explicit … Julie Christie, Donald Sutherland and Nicolas Roeg filming the sex scene in Don’t Look Now. Photograph: Studio Canal/Rex/Shutterstock

It’s vital to know the context in which Roeg and Bertolucci’s films were released. Though candid and unflattering sex scenes were already a staple of the American new wave (they are especially important to Bonnie and Clyde) and the European arthouse, that wasn’t the whole story. Soft-core pornography and risque sex comedies were still an acceptable and lucrative part of mainstream cinema programming in Britain. In those pre-multiplex days, at least one auditorium at every local three-screen cinema would be given over to some dubious enterprise with an innuendo-laden title, so that children queuing with their parents to see Pinocchio or The Rescuers would file past posters for Don’t Get Your Knickers in a Twist and Thigh Spy. Martin Scorsese’s Taxi Driver may have been attracting plaudits in 1976 but it was comfortably outgrossed in British cinemas that year by Adventures of a Taxi Driver, a listless comedy featuring a thoroughly depressing sex scene intercut with shots of the meter running in a waiting cab.

Decades of late-night TV screenings of Don’t Look Now, not to mention that film’s rise to the top of assorted polls assessing the greatest British films of all time, have worn away its shock value. It is important to appreciate not only how strange Roeg’s film would have looked at the local ABC next to, say, Fresh, Young and Sexy, but also its sheer radicalism in treating screen sex as a means of deepening the characters’ psychology. As Peter Bradshaw pointed out in an appreciation of Roeg, Don’t Look Now contains one of the few movie sex scenes between characters who already know one another; they’re enriching an existing bond rather than tearing off each other’s clothes in the heat of a newfound passion. Not only are Donald Sutherland and Julie Christie playing a married couple, but their lovemaking represents a healing, because they have come to Venice partly to recover from the death of their daughter.

Sheer radicalism … Christie and Sutherland in Roeg’s film Don’t Look Now. Photograph: TCD/Prod DB/Alamy Stock Photo

The scene also serves an important and mysterious function within the plot – and here I can only say don’t look now if you haven’t seen Don’t Look Now – since it was always Roeg’s contention that it marked the moment at which Christie becomes pregnant again. Though this is never mentioned in the film, Roeg viewed the final shot of her in the funeral procession as a moment signalling an imminent birth. Confessions of a Window Cleaner never quite brought that sort of complexity to a bit of how’s your father.

Last Tango in Paris looks very different knowing how Schneider was mistreated and manipulated

It would be wrong to suggest controversy didn’t play its part in attracting audiences to the films of Roeg and Bertolucci, although sometimes it could threaten to capsize a film. Producer Jeremy Thomas, who worked with both directors, recalled the furore at the Rank Group, which financed Bad Timing, Roeg’s disturbing 1980 drama about a destructive sexual relationship. One scene in particular, in which Art Garfunkel has sex with Theresa Russell after she has taken an overdose that may yet transpire to be fatal, was necrophilia in all but the letter of the script. “Rank had started out distributing religious films,” Thomas said in 2014, “and you couldn’t get much farther than Bad Timing from the ideology of Lord Rank. When the chairman finally saw the film, he threw his hands up and said, ‘The Gongman is coming off that film!’ And so it opened with no trademark. George Pinches, who was at the time the head of the Rank circuit, called it, ‘a sick film made by sick people for sick people.’”

Bernardo Bertolucci, left, with Marlon Brando while filming Last Tango in Paris in 1972. Photograph: Granger Historical Picture Archive/Alamy

Bad Timing is safe now from such besmirchment, and Roeg’s reputation has rarely been greater, thanks in part to the adulation of younger directors such as Christopher Nolan and Danny Boyle. Bertolucci is a different matter. Last Tango in Paris is a magnificent piece of cinema, but it looks very different now in light of the revelations about the way Schneider was mistreated and manipulated by her co-star and director – revelations the actor herself, who died in 2012, discussed openly in interviews as far back as 2007 but which only gained widespread traction once they were ratified by Bertolucci in 2013. He admitted that he and Brando had cooked up together the idea of using butter as a prop in the film’s anal-sex scene, surprising the then 19-year-old Schneider with it while the camera was rolling because he “wanted her reaction as a girl, not as an actress”. Schneider said she felt “a little raped” after the scene was finished. “I was so angry. I should have called my agent, or had my lawyer come to the set, because you can’t force someone to do something that isn’t in the script. But, at the time, I didn’t know that. Marlon said to me, ‘Maria, don’t worry, it’s just a movie.’”

But Last Tango in Paris can’t just be a movie any more. Unlike Roeg, Bertolucci kept on making exceptional work later in life, such as Besieged, The Dreamers and his 2012 swansong Me and You (completed seven years after he suffered a debilitating back injury). All that is in danger of being overshadowed now that audiences in the #MeToo era can point to Bertolucci and say: “Him, too?” What happened on the set of Last Tango in Paris, not to mention the years of Schneider’s claims being ignored, undoubtedly complicates the period of thriving experimentation in which that picture was made. And though it isn’t the first great work of cinema to be built on suffering, it is one that many viewers today won’t be able to look at without seeing only the wrongs perpetrated in its name.