* "Nordic Noir" captures fans worldwide, but why?
* Actress hopes it is quality of drama, its "humanity"
* Best-known global example is "Girl with Dragon Tattoo"
By Nigel Stephenson
LONDON, Feb 3 (Reuters) - Millions of people around the world have become avid fans of what is known as Nordic Noir detective and crime stories set in Scandinavia, with the next question after whodunit being why are they so successful?
"The Bridge", a subtitled Danish-Swedish eco-terrorism crime saga reached its conclusion on British television on Saturday with more than a million viewers - the latest international success for the TV, film and literary genre.
Coinciding with the show's climax, a weekend "Nordicana" conference of all things Nordic, from actors to food, brought many of the genre's unlikely stars to London where one of the questions they were peppered with was: why does this work?
"I hope it's the quality of the drama and the essential things of humanity that you can imagine in all countries," said actress Sidse Babett Knudsen. Playing the role of Birgitte Nyborg, she became Denmark's first, if fictional, female prime minister in the first season of the political drama "Borgen".
Life later imitated art and Helle Thorning-Schmidt, whose "selfie" with U.S. President Barack Obama and British Prime Minister David Cameron at Nelson Mandela's memorial service made headlines, became Denmark's first real female premier in 2011.
Nordic Noir has a long vintage.
Perhaps the best known recent success was Stieg Larsson's Millennium series of novels, starting with 2005's "The Girl with the Dragon Tattoo". They have sold more than 60 million copies and been made into Swedish and U.S. films.
But for Nordic TV drama, the lodestone was "The Killing" first produced by Danish public broadcaster DR in 2007 and starring Sofie Grabol as Detective Inspector Sarah Lund.
"We would be nowhere with a series like 'Borgen' if it hadn't been for 'The Killing'," Babett Kudsen told Reuters.
"The Killing" has been sold in more than 135 countries and territories, led to a U.S. remake, and made Lund's trademark rustic knitted jumpers a fashion item.
Piv Bernth, the show's producer and now DR's Head of Drama, told Reuters by email that "The Killing" created a new way of telling a crime story.
"One killing in 20 episodes - you had to wait until the end if you would find out who did it," he said. "At the same time, we told a profound story about people and destinies in a modern society."
At the Nordicana festival, among stalls selling open sandwiches and Swedish jewellery, one fan wore a Birk Larsen Removals T-shirt, a nod to a murder Lund solved in Season 1.
There are common themes to Nordic Noir. Strong female characters reflect the emphasis on gender equality that is part of the so-called Nordic model rooted in high levels of social protection and defence of human rights.
There is winter. "We have a darkness in our landscape that comes through in our writing, our directing and our acting and is at the very core of the Nordic Noir thing," said Adam Price, the Danish writer of Borgen, who is also a TV chef.
There is the contrast between the image of a wealthy region that topped the United Nations World Happiness rankings in 2013 - Denmark was first, Norway second and Sweden fifth - and the real problems dealt with in the dramas.
"There is no paradise on earth...the Swedish system is becoming less and less secure and more and more people are living harder lives," said Sofia Helin who plays the near-emotionless, Porsche-driving detective Saga in "The Bridge" told Reuters.
"Borgen" writer Adam Price said part of the dramas' success was due to the fact that DR had commissioned multiple episodes at a time, allowing complex long-running storylines to be woven over weeks.
"We can build the arc around the characters in a much more elaborate way," he told Reuters.
But a state broadcaster's backing brings its own problems. "Borgen" producer Camilla Hammerich said plots had to be balanced to ensure no bias.
There was even a debate about whether a right-wing party leader could be shown wearing "ugly" shoes. (Editing by Michael Roddy and Tom Heneghan)