IT IS THE BBC'S most brooding period piece complete with tousle-haired Byronic hero – regularly stripped to the waist – feisty female leads, dramatic Cornish cliff tops, shipwrecks and sizzling sexual tension.

Poldark, which has attracted audiences of up to 6.7 million viewers, returns tonight with producers predicting the series – set against a background of the American Revolutionary War and the French Revolution – will be as big a hit as ever.

Based on the iconic 12-strong series of historic novels of the same name written by Winston Graham, Poldark was first adapted for TV in the Seventies. The latest adaptation, which kicked off in 2015 starring Adrian Turner and Eleanor Tomlinson, has attracted super fans across the world.

Now in its third series and set in 18th Century Cornwall and France, it continues to follow the trials and tribulations of Captain Ross Poldark and his explosive relationship with his miner's daughter wife, Demelza. Further intrigue focuses on the pregnancy of his first love Elizabeth (Heida Reed) with speculation rife that despite her marriage to George Warleggan (Jack Farthing) the child is Poldark's.

Their relationship was consummated in a controversial scene in series two, dividing fans and commentators. Writers and actors insisted the sex depicted was consensual, while others expressed fears about the "dangerous message" portrayed by the "rape scene" which saw Poldark break into Elizabeth's bedroom and repeatedly ignore her requests to leave before carrying her to the bed.

Andrew Graham, the son of the novelist behind the cult series, who has acted as a production advisor and robustly defended last year's divisive scene, said that he was excited by what he had seen of the most recent series.

"The novels have huge drive at this stage so I'm very optimistic of its success," he told the Sunday Herald. "It's been wonderful to see how authentically the adaptation has stuck to the books."

Commentators have pointed to the continued rise of dramas such as Poldark as of evidence of the need for escapism. From sizzling period dramas to "fluffy" cult hits like the Bake Off, which has seen viewing figures of 10m, it is said we are looking for light relief from right-wing politics, terrorism attacks and austerity.

The rise of period drama – from Downton Abbey to Victoria, Call the Midwife and War and Peace – was attacked by film maker Ken Loach last year. The director of I, Daniel Blake said the message sent was: "Don't bother your heads with what's going on now, just wallow in fake nostalgia...It puts your brain to sleep."

However Graham insisted only part of Poldark's appeal was escapism, with the universal themes of love, loss and the fight for equality keeping viewers coming back for more. "It's a very gripping story that people can relate to at different periods in their lives," he said. "On one level it's a love story, but it's also about rich and poor. In a time where we are talking about bankers and those suffering from austerity that seems all too relevant. It's about hope, about striving and failing."

Damien Love, the Sunday Herald's TV critic, agreed that while Poldark dealt in nostalgia there was more depth than first met the eye.

"There's a kind of satisfying, shady, guilty-pleasure Catherine Cookson throwback appeal," he said. "[But] when it arrived Poldark really felt like the first proper period drama in ages, because it was just so unashamedly, old-fashionedly thrilling, with tons going on plot wise and proper baddies with proper baddies' evil faces, like 1960s Bond villains. There were duels and dastardly deeds and thwarted romance and brooding heroes.

"While it's all fairly simple and on the surface, there's also some complexity there if you want to dig for it."

It is also solidly rooted in history. Consultant historian Dr Hannah Greig of York University said Graham had used real historical records, such as court ledgers, as the backdrop for his fictionalised characters, giving the series an appealing authenticity.

Faye Woods, lecturer in film and television at Reading University, said populist period dramas both helped a broadcaster "assert prestige" and engage in a traditional Sunday night fight for ratings.

However she claimed the new crop, often written by talented female scriptwriters such as Poldark's Debbie Horsfield, were responding to a public "thirst" for stories about the emotional experiences of women and dealt with the complexity of female pleasure and desire.

"This is why they are often disparaged culturally," she added. "Call the Midwife is all about women's labour – physical and emotional – and the place of the NHS in society. Poldark itself is solidly about his fight for the community and the rights of the people against the wealthy, as well as attending to the female gaze."

However Liz Ely, co-director at Zero Tolerance and founder of the Write to End Violence Against Women Awards, said she remained troubled by Poldark and renewed calls for writers to work with experts from the women's sector for future scenes.

"In reality the line between consensual sex and rape is not ambiguous and this kind of storyline can have damaging, real-world impacts," she said. "The writers on Poldark have had an opportunity to listen and learn from the criticism they received – we hope they have used it."

Poldark, Series 3, is on BBC1 tonight at 9pm

Timeline

1945 to 1953: Winston Graham published his first four historical novels in the Poldark series, set in 1790s and early 19th Century Cornwall.

1973 to 2002: After a twenty-year hiatus Graham returns to complete another eight books in the series set in the early 19th Century.

1975: The BBC make the first adaptation of the series, starring Robin Ellis and Angharad Rees.

2015: Rights are re-acquired for a second adaptation of the now classic drama.