Birgitte Hjort Sorensen: Borgen's back! Meet one of its stars

The Killing is dead, and Downton Abbey and Homeland are over for another series – but at least this week sees the return of Borgen, the Danish political thriller.

The story of a female prime minister struggling to hold together her coalition and her family was a surprise BBC4 hit last year. Prime Minister Birgitte Nyborg (Sidse Babett Knudsen) starts series two on Saturday trying to enhance her political reputation abroad, after her government is rocked by coalition splits back home. Viewers were kept in suspense at the end of series one over whether she would get back together with her husband, Philip Christensen (Mikael Birkkjaer), who told her his affair with another woman was because her premiership had challenged his masculinity.

Borgen's critical acclaim in the UK – it was voted sixth best show on TV by a poll of critics for the Radio Times – is partly down to the strong female characters, including the headstrong journalist Katrine Fonsmark.

But Birgitte Hjort Sorensen, who plays Fonsmark, says the UK success was "quite a big surprise for us" in Denmark, particularly because the notion of powerful women is not extraordinary in that country. Earlier this year, Denmark's real-life female prime minister, Helle Thorning-Schmidt, said university-educated women in Britain were "wasting" their degrees by becoming stay-at-home mothers. And Sorensen says: "Strong female leads make more of an impact in the UK than in Denmark."

Sorensen refuses to give away any spoilers for series two, only that things will be a "little bit different". Her character has left the TV job and is now a reporter for the Ekspres newspaper. "Over the course of the series she believes that compromise is necessary. She realises that life is not black and white."

Similarly, Nyborg must make compromises in her government to keep it together. "She [Nyborg] does compromise but that is a strength," Sorensen says. Everyone who gets the job of prime minister in a coalition has to compromise."

Sorensen, 31, spent time working with journalists in Denmark to research her character, but she says: "In the UK, journalists are a little bit more ruthless than in Denmark. I have a feeling the tabloid press in the UK is pretty harsh."

Borgen for beginners

Borgen (translation: "Fortress") is the name of Denmark's government buildings and the new PM, Birgitte Nyborg, struggles to put together a coalition. When she does, her husband, Philip, who has to give up his executive job to be a stay-at-home father, has an affair because he cannot cope with her success. Her spin-doctor, Kasper Juul, causes her trouble by leaking stories to his ex-girlfriend Katrine Fonsmark, who dated another spin-doctor who died in her bed.