How does Danish TV company DR keep churning out the hits?

The Killing, Borgen, The Bridge...Gerard Gilbert goes inside the Danish TV hit factory.

On the set of The Bridge, DR's latest successfully exported TV series (Ola Kjelbye)

Only VIP fans are allowed on the set of The Killing 3. Camilla, Duchess of Cornwall, was presented with a 'Sarah Lund sweater' by actress Sofie Grabol when she went on location in Denmark earlier this year, but commoners – especially journalistic ones – are barred from entry. "The crew find it distracting," explains the press officer for DR, the Danish state broadcaster responsible for The Killing, the political drama Borgen, and now, our latest imported Saturday night treat, The Bridge.

But then, as much as I would like to hang out with Lund (and loved the way in which Grabol had a holstered revolver insouciantly slung round her waist as she chatted to Camilla), I am actually in Copenhagen to meet the creative brains behind the hit shows that have put Danish TV drama on the map. I wanted to know what they were doing right in order to produce hit after hit, and whether our native broadcasters could learn anything from their success.

A short taxi drive from the airport, on reclaimed marshland to the south of the city that has the feel of the London Docklands (complete with the same elevated railway), DR's shiny, black-clad quayside headquarters are being whipped by an icy Baltic wind that swiftly makes you realise the wisdom of Lund's preferred knitwear. In the warmth of the reception area, clusters of children are waiting for the recording of the Danish version of The X Factor – for DR is not just in the job of creating quality drama. Shows like The Killing and Borgen are not broadcast on a minority channel in their homeland, but on DR1, Denmark's equivalent of BBC1.

"We are a public service broadcaster," says Morten Hesseldahl, DR's cultural director. "We have to be just as entertaining as commercial competitors but at the same time we need to have a social-political dimension in our serials."

The third season of Borgen, which follows the fortunes of Denmark's first fictional female prime minister (the country has since acquired a real one), is currently being shot somewhere in the bowels of the building, where a TV newsroom has been mocked up. In the show's upper-floor production offices, complete with scrawled-on whiteboards on which the logistics of the plot are calculated, and a montage of stills featuring Hong Kong (prime minister Birgitte Nyborg visits China in Borgen 3), series producer Camilla Hammerich further elucidates DR's philosophy. "We have to tell what Ingolf [Ingolf Gabold, the veteran head of DR drama] calls 'the double story'. It could be crime or family drama, but on top of that we have to tell something more about society, about ethics. It is kind of old-fashioned, isn't it? Well, it kind of has an educative purpose."

In fact it's what, in the context of the BBC, would be called Reithian – or at least the socially liberal offshoot of Reithianism that encouraged the flowering of Play for Today and a golden generation of writers in the 1970s and Eighties, but which was lost when market forces and political paranoia swept through the Corporation in the 1990s. And just as American cable channels have found success by giving primacy to the writer, DR champions what it calls 'One Vision'.

"One Vision means that you believe in the author and their vision of the story," says Morten Hesseldahl, "so they don't have to be manipulated by management or by directors, and I think that is what is going wrong in a lot of places. As far as I can understand from some of your creative people, they have recently become frustrated – there are too many people trying to have an opinion about what they are doing."

"The great thing about DR is that they really understand the necessity for artistic freedom," agrees Borgen's creator, Adam Price. "We do not have executives popping in every minute into the writers' room." We're talking in Price's handsome villa in the north of Copenhagen, drinking formidably strong coffee in a kitchen that has recently been remodelled so that it can work as a television studio. For, apart from writing Borgen, Price is Denmark's foremost TV chef. It's as if Steven Moffat, in between writing Sherlock and Doctor Who, moonlighted as Jamie Oliver.

Price is pronounced Pri-se in Danish, the family of entertainers having emigrated to Copenhagen from London in the 1790s. After working as a staff writer on the seminal Nineties DR series Taxi, he created the hit relationship drama Nicolag and Julie, in which Julia was played by Sofie Grabol of future Sarah Lund fame. Price then left his show to become head of drama at DR's commercial rivals TV2 (where he worked with Camilla Hammerich), handing over the writing reins on Nicolag and Julie to Soren Sveistrup, who later created The Killing – all of which gives an idea of the tight-knit pool of top talent in Danish TV drama.

"Adam and me have been working together for something like 15 years," says Hammerich. "We've been on other TV stations together, so we know each other like an old married couple, and it's like that with Piv Bernth [producer of The Killing and now head of drama at DR] and Soren Sveistrup, the creator of The Killing, they have an old marriage as well. I don't know whether that's the secret of our success but that's a fact."

Equally recyclable is the pool of top actors, with a few of the same performers featuring in different shows, most notably in the case of Soren Malling – both Sarah Lund's cop partner in The Killing and the TV news director in Borgen – and Mikael Birkkjaer – Lund's partner in The Killing 2 and prime minister Brigitte Nyborg's husband, Philip, in Borgen. And eagle-eyed viewers of The Bridge will have noticed Nicolaj Kopernikus – shifty removal man Vagn in The Killing – in a cameo as a homeless man.

"I just read an English newspaper article entitled 'Has Denmark run out of TV actors?', and I guess it appears this way," says Birgitte Hjort Sorenson, who plays ambitious young news anchor Katrine in Borgen, during a break in filming. "I went to school with Pilou [Johan Philip Pilou Asbaek], who plays Kasper, and I was in the year above him at drama school, so we've met a lot over the years, but most of the others are new to me."

Although a female writer has joined the team for the third series of Borgen, a show in which the two main protagonists are women, the first two seasons were written entirely by men. "A lot of the shows we've had [in Denmark] have had strong female characters and female leads," says Sorenson. "I don't know why – maybe it's just not an issue any more because I don't think we are feminists or anything."

However, DR's cultural head, Morten Hesseldahl, thinks that the way the dramas reflect the complexity of modern society is one of the reasons for their success. "I think that the Scandinavian countries are a little ahead in speaking about family life," he says, "about working mothers and extended families – which is normal in Denmark. I think it gives a flavour to the stories that makes them interesting to audiences abroad."

Mainly, however, Hesseldahl puts the success of DR's dramas down to the care lavished on the scripts. "I used to be the chairman of the board of the Danish Film Institute and I think the problem with Danish film production is that they go into production too soon before the script is developed and I think what has been the success here is that we are working on the script again and again and again."

With an annual income one-eighth of the BBC's, every project has to be a winner – with a strict policy that there should be no re-makes or adaptations. And even where DR outsources production – as it does with The Bridge – the company keeps a tight eye on quality control. What does he see as a possible danger ahead? "Being too consumed by our own genius," he says. "That's why it's important for us that we try to shift genre – so we have made a thriller and a political drama, and now we are going to make a historical drama."

The drama in question is 1864, about the war between Denmark and Bismarck's newly unified Germany that led to the perpetual loss of Schleswig-Holstein to the victorious Germans. "The war was very defining for the character of being Danish [because] we lost so much there," he says. "Ever since it has made an impact on the sense of Danish self-understanding." But costume drama is expensive, and at £2m for each episode, DR is looking for foreign investors. "We are talking with the Germans – as this is actually one war that Germany won."

A second new drama, Veronica, will look at Danish cultural life since the Second World War, and Hesseldahl is well aware that this, and a painful period in Denmark's history, may be of limited interest to foreign viewers. "I think we should be courageous enough to accept that we could come up with a TV series which does not have this huge appeal that they have had up to now, and to accept we are only reaching 700,000 and not 1.5 or 2 million Danes. But if we are getting too nervous about delivering high ratings then we wouldn't be courageous enough to come up with something new."

That sort of courage – admittedly fortified by a licence fee that costs each Danish household £250 a year (£100 more expensive than the British TV licence) – resulted in Borgen, a domestic political drama with potentially little international appeal, but which is now being re-made for American TV (as was The Killing), re-cast amid the state-level politics in Virginia. Adam Price, who is acting as a consultant on the US remake, recalls the difficulties faced in commissioning the Danish original. "The DR bosses were hesitant because they thought it was risky to do only politics Sunday at 8pm, because they were so successful doing police shows," he says. "They were afraid it would be too narrow and only interest 200 or 300,000 people and that is not enough."

As it happened Borgen attracted more viewers when it debuted on BBC4 than either series of The Killing. The next series will be the last – as it will be the final showing for The Killing and The Bridge. What does Price himself have in mind for his next new drama? "I have some ideas," he says. "I'm very interested in religion, so I might go that way."

Religion might be an even harder sale than politics, even on a Sunday, but I wouldn't put it past Price and DR to come up with a compelling story. "But a good story is not enough," he says. "You need an ambition to tell us something about our time, how it is to live right now a Dane, a European... the great choices of life right now. You have to think big, but the story must also work on the smaller scale."

In the meantime, the Duchess of Cornwall and Prince Charles will only be two among many Britons hunkering down to watch The Killing 3, and Sarah Lund's swansong. I may not have been allowed on set, but Hesseldahl does give me one titbit. Lund will find love at last. "There is going to be more of Sarah Lund," he promises, "also something from her past. I don't think you would have seen a Sarah Lund in a commercially-produced TV series."

"You cannot plan yourself to a success," he summarises, looking out of the deeply-glazed windows as the afternoon thickens over Copenhagen. "Only try to be in the place when the timing is right and then you can look back and tell the story which explains everything. There is a lot of luck involved in what happens."

'The Bridge' continues on Saturdays on BBC4