Polish actress Anna Prochniak said filming The Tattooist Of Auschwitz on a TV set built to look like a concentration camp was “very challenging”.

The six-part series is based on the bestselling novel from Heather Morris inspired by the real-life story of Lali Sokolov and Gita Furman, who met while prisoners in the Auschwitz-Birkenau concentration camp during the Holocaust.

British star Jonah Hauer-King and Prochniak, who led the cast in the roles of Lali and Gita, appeared at the London premiere of the series, alongside director Tali Shalom-Ezer and author Morris.

Prochniak told the PA news agency that filming the series took a toll.

“I think going back every day into these camps, back into the mindset for five months every day, it was very challenging for all of us, it took its toll on everyone,” she said.

Talking about her character Gita, she added: “What I love about her is how multi-dimensional she is and how complex she is.

“She’s vulnerable but at the same time so very strong and her fragility is deeply moving and her resilience is something that I admire about her so much – she is a true inspiration.”

World On Fire star Hauer-King said preparation for the show was “more than anything I’d ever done before”.

“There was a huge amount of historical research which involved going to Auschwitz camp itself, it involved reading survivors accounts and documentaries,” he told PA.

“And then the other part of the preparation was about this story specifically, and getting to know Lali through his testimony in the 90’s and his testimony to Heather (Morris) and having the chance to talk to Heather Morris myself.

“There are challenges in making TV drama when you have a story like this because you’re first and foremost wanting to take care of it and do it in a way that feels respectful, while also wanting to make a show that feels compelling and gripping and keep audiences with you, and so it was all about striking that balance – but we were in good hands.”

Hauer-King described it as a “huge challenge every step of the way” to tell the story sensitively, but added it was a “great honour and a huge privilege”.

The adaptation follows the story of an older and recently widowed Lali aged in his 80s, played by Oscar-nominee Harvey Keitel, recounting his story and relieving his memories of falling in love to aspiring writer Morris, played by Melanie Lynskey.

Director Shalom-Ezer said it was a “long, crazy journey” in telling this intimate love story.

“Everything was difficult about it … telling a story on such a large scale so every single scene we had to have hundreds of supporting artists, sometimes we’d shoot outside in the cold, just very confronting the content so that was the most difficult thing,” she told PA.

“This is a very hopeful story, Lali and Gita are both optimistic and I just had a lot of admiration to their ability to believe in love and to believe in life and even though they went through such a dehumanisation process, they still kept themselves as human beings and this is incredible to me.”

Gary Sokolov, the real-life son of Lali, described the process as “emotionally draining” but said it was a life-long dream to have the story told on the big screen.

“People need hope in their life,” he added.

The series will premiere on May 2 on Sky Atlantic and streaming platform Now.