Ita O'Brien consulted the lesbian "Karma Sutra" for Suranne Jones" sex scenes in "Gentleman Jack".
The 54-year-old "intimacy coordinator" has been working with the actress - who plays landowner Anne Lister - on the BBC's historical drama, and Ita has opened up about the research she carried out for the racier moments in the series.
Revealing a copy of "The Whole Lesbian Sex Book", she told The Sun: "I had to do quite a lot of research for "Gentleman Jack". I used the lesbian Kama Sutra too.
"The important thing was to have a template -- if you have a text that explains what positions the women favour and how they make love, then you can really honour that.
"I spoke openly about body parts, and choreographed the scene through to orgasm, using anatomical language, so everything was dealt with openly in an adult fashion."
She added that there is more to consider than just basic outline of raunchy scenes in a script, and Ita - who also worked on Netflix original "Sex Education - explained the importance of giving more details to actors.
She said: "Far too often the writer just writes, "They have energetic sex", and you're left thinking, "What do they mean?" It's like if you put in a musical, "They sing".
"Well, what are they going to sing? How are they going to sing it? What's the melody? What are the words?"
Meanwhile, Suranne has previously opened up about how helpful Ita was when it came to making her feel comfortable.
The "Doctor Foster" star said: "One of the great things she brought was an articulacy - we could talk about the scenes. She just started talking about body parts and positions in a matter of fact way, which just liberated us all.
"As well as helping us sculpt the sex scenes, the positions, she's also there to provide support to the artists."