Jane Austen "would have loved" ITV's version of her unfinished novel Sanditon, says literary expert

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So would Austen herself have approved? "An emphatic yes," the show's literary advisor Dr Byrne tells RadioTimes.com. "I think she would have loved it, and I think she would have loved the lavishness and the beauty of the production. I think she would be writing for Hollywood if she was alive today."

Besides, Austen was racier – and more groundbreaking – than many viewers might think.

"I do think her novels are really sexy," Dr Byrne says, referring back to Pride & Prejudice: "I mean, Lydia Bennett, she's 15 and she's living in sin, she's screwing Wickham and everybody knows it. Other than Darcy, nobody seems to really care.

"She's not punished. A lot of novels, if a 16-year-old girl is seduced or having sex, she's sort of punished. Jane Austen emphatically did not punish Lydia. In fact Lydia gets exactly what she wants. And so she's not, 'let's punish women because they like having sex'."

Then there's Sir Edward Denham, who arrives in Sanditon with his sister Esther. As Austen writes, he has a plan to "seduce" Clara and "undermine her principles" and force her into "the quietest sort of ruin and disgrace", purely to undermine her rival claim to Lady Denham's fortune. The implication is clear.

In the unfinished novel, there is no mention of an incestuous relationship between Edward and Esther. But Dr Byrne does not think it out of the question that Austen would have written a similar storyline – especially if the two were step-siblings rather than blood relatives.

"People forget that in the 18th century, a lot of women died in childbirth which meant that a lot of people remarried, and they had half and step-siblings... it wasn't that uncommon," she says.

In fact, one of Austen's contemporaries was the novelist and diarist Fanny Burney, whose brother James and half-sister Sarah were rumoured to have had an incestuous affair when they spent five years living together as adults.

So could Austen actually have written incest into Sanditon? "Who knows?" says Dr Byrne. "But as I say, I wouldn't be at all surprised if she went down that line. It wouldn't surprise me one bit. She was a great fan of Fanny Burney, she adored Fanny, she would have known about Fanny Burney's sister's incestuous relationship because everybody knew about it...

"I don't think it would have shocked in the way that it shocks now... So it's wrong to read back anachronistically and think, she was a prude or she wouldn't have gone down this particular road, because I just don't think it's true."

Then there's Miss Lambe, who really does appear in the novel as a mixed-race “young West Indian of large fortune." This was quite a bold move by Austen.

"Introducing Miss Lambe, I think, is really fascinating," says Dr Byrne "I'd love to see where she would have taken it, because [Sanditon] just has such a different feel to it, it just has a lot of – even though she was dying, such energy. There's an energy about the fragment of the writing, and I think the production really captured the energy.

"And to have a mixed heritage girl – which people would would find very shocking because she's there, she's in the manuscript, and what would she have done with her is fascinating.

"Jane Austen knew lots of families who owned plantations, so she knew there were lots of mixed relationships in the late 18th century. She knew people, so she knew of Dido Belle for instance. Dido Belle, who was raised by Lord Mansfield as a lady, who was mixed race. So I feel like Miss Lambe is a sort of Dido Belle character."

Dr Paula Byrne's previous works include The True Story of Dido Belle; Jane Austen and the Theatre; The Genius of Jane Austen; and The Real Jane Austen: A Life in Small Things. She joined the team as Sanditon's literary advisor, alongside Dr Hannah Greig as historical consultant, and her job was to spot un-Austen-like red flags.

"I don't think my role was to change anything major, but just to point out that there may be some controversy and be prepared for it. But I think that's good actually. I think that's a good thing, to have some controversy," she says.

"The safe, cosy Jane Austen... I think anything that really shows that sort of irreverence, that darkness in Jane Austen – sometimes we call it regulated hatred. There's a famous essay saying that Jane Austen would have despised the people who read her novels, and I slightly agree with that view!

"They're sort of 'frocks and smocks' and people wanting a reprise of Elizabeth Bennett, and I just don't think that's what she's about. I don't think it does her any justice, and what I really loved about this production of Sanditon was it's kind of pushing at the edges of that argument."

If the author had lived long enough to complete the manuscript, Dr Byrne is doubtful she would have continued the story of Sanditon in the way we've seen on screen ("probably not!") – but that's not to say Davies is untrue to the spirit of Jane Austen.

"He just has such a feel for the language, and he has such a feel for the characters, and I feel like he has the irreverence that she had," the academic explains. "He can be very funny. She was laugh out loud funny, Jane Austen."

Sanditon continues on Sundays at 9pm on ITV