One week after I interview Kirsty Wark, the BBC broadcaster becomes a trending topic on Facebook and Twitter.

One newspaper's tweet says it is the video "everyone is talking about".

The clip, from the Halloween episode of Newsnight, showed Wark providing the LOLs by dancing to Michael Jackson's Thriller - full-on werewolf style - along with a group of bloodied zombies, dancers from Tiffany Theatre College in Essex.

It's funny. One friend remarked that it would have been even more amusing had it been Jeremy Paxman, her Newsnight co-host; but I love that it's Wark, a woman who is at once steely-eyed and serious but with a cracking sense of humour; who is just as at ease discussing Syria with Kofi Annan as she is doing a cameo in Absolutely Fabulous. These flip sides are Wark all over. A book-loving intellectual who is just as happy reading Grazia as she is The Spectator. Someone who appreciates the arts as much as politics. A woman confident enough fulfilling female stereotypes - that of lipstick-loving, home-baking wife and mother - as she is breaking them.

It shows she's kind of cool.

When we meet at the grand terraced house she shares with her husband Alan Clements, director of content at STV, in the west end of Glasgow, Wark is dressed down in jeans and no make up.

"I'm in a very privileged position to be a presenter in the BBC so you have to take the job seriously," the 58-year-old tells me over coffee in her front room. "I just don't think we have to take ourselves too seriously. If I make a mistake, that's bad; but if a brain surgeon makes a mistake, it's fatal."

You can't come home and beat yourself up if you've had a bad interview, I suggest. "Oh, you can," she counters. "Post-match analysis is often quite tough." It can play on her mind at night. "I think about things - things I could've done better, a question I could have asked a different way - always."

Recently she was accused of being "cringe-inducing" and "spluttery" by media commentators when interviewing Glenn Greenwald, the journalist at the centre of the Edward Snowden NSA leak.

So how does she handle criticism? "If it's constructive, I absolutely take it on board."

Having hosted Newsnight for more than two decades, as well as fronting The Review Show for half that time, Wark has interviewed everyone from Harold Pinter to Madonna. As a journalist interviewing a fellow journalist, I envy her; not least because she interviewed my favourite author - Toni Morrison, best known for her Pulitzer Prize-winning novel Beloved.

"And what a great woman she is," says Wark. "She is tremendous. For somebody who has been interviewed so many times, she always is very gracious and giving."

Wark would have been paying attention. She's always fancied becoming a fiction writer one day and her first novel, The Legacy Of Elizabeth Pringle, is out next year. She's working on her second one, set in Scotland and New York. It's a change of tack for the broadcaster, one that has led her away from the "precise and concise" world of journalism she's inhabited for four decades, and for which she will receive a Scottish Bafta for Outstanding Contribution to Broadcasting next weekend. "It's a tremendous accolade and I feel very privileged and humbled," she says.

With that, the dog walker arrives to take Pepper the ageing black Labrador out, just as we begin discussing her career highlights. The Morrison interview is one; and "people talk about the [Margaret] Thatcher interview," she says, but "it was so many years ago, it feels weird to talk about that."

For her part, Baroness Thatcher was, according to Wark, "deeply angry" at being interviewed by a woman. It took place in 1990 and one could say it was the game-changer in which Wark cut her interviewing teeth. It would become one of many encounters Wark would have with politicians. Her first interview with Alex Salmond, she says, "went wrong for a variety of reasons, not just editorially but technically", culminating in Wark apologising to him afterwards.

The pace of our chat slows momentarily as Wark reflects. She likes covering the big things, she says - the referendum, General Elections and the opening of the Tate Modern. Her interview with Aung San Suu Kyi was also a "privilege". But, after some consideration, she says, "One of the things I hope I have been able to achieve is, if I've had to go somewhere that's had a dreadful disaster …" - such as Lockerbie - "to be restrained. I believe it is not my role to ever emote. If I'm somewhere, it's because I need to tell a story quietly, without too many adjectives. It's not my pain, it's their pain. I'm uncomfortable with over-emotional reporting. Sometimes it's unavoidable but it's our job to be compassionate - but dispassionate - and to be restrained."

If Wark's emotions have ever gotten the better of her, it's only in so much as she's allowed herself to be riled by a provocative politician. (A case in point: interviewing Michael Portillo in 1994. Although, looking back, she says she was "raw" from going back to work too soon after her father's death and, two weeks later, her godmother's death. "I should've taken another couple of weeks. There is no justification for a bad-tempered interview.")

For viewers, it is easy to forget that Wark is the host; that the topics discussed stem not only from her, but from team discussions behind the scenes - the alchemy of which is a process she finds as enjoyable as doing the interview.

People, she says, think "it's either all me, or it's in my earpiece. But, no, that's not how it happens. That's never the case," she explains. "I'm meant to be the slightly calm person in the front, but there are tons of people working on great stories for Newsnight and The Review Show."

Wark aims at being the consummate professional. "Obviously when [bad] things happen you feel, 'Wouldn't that be awful if that happened to somebody close to me, or my child?' You can feel that," she concedes. "But you absolutely have to step back."

She recalls the time she interviewed Gerry and Kate McCann, the parents of missing child Madeleine. "You talk about when it was difficult …" She trails off. "Because they're such dignified people. Why would I interpose my own feelings?"

When she is at her best on live television, interviewing politicians and public figures, her words are fired out like bullets - rapidly and directly. In person, and it may be subconscious, she'll often stop short of finishing a sentence, either because her brain is working so quickly, she's already on to the next thought (she talks quickly), or because, maybe sometimes, she doesn't want to fully commit to the opinion she's giving. I surmise this is likely an effort to be open-minded and see different points of view, no bad thing. She has, formerly, been accused of political bias (that's another story).

As she and the rest of the country move toward the referendum, Wark will want to be seen as balanced. If she is leaning one way or the other, she's not going to tell me and I know better than to ask. Her view, for the moment, is that we need to keep talking about it. "Because suddenly it's next September," she smiles. "We need as much informed opinion as possible. It's a momentous decision. And it's not one just for Christmas, do you know what I mean?" I think I do.

But BBC Scotland is "getting up to speed", she says, in that it has appointed John Mullin, former editor of the Independent On Sunday, to lead its independence coverage. Wark's turn of phrase perhaps references the fact his appointment was only made in September, when there was little over a year until the vote. Not soon enough, some may say.

Wark, for her part, gains an interesting perspective on the referendum as one who lives in Glasgow but works one or two days a week in London, where, she finds, there's a "slight distance and bemusement about it all; a kind of shrug of the shoulders".

Wark never felt the need to move to London for her career, and it's only when discussing this that she perhaps offers some hint at her feelings towards the Union. "I've never been a person who thought the United Kingdom was London-centric," she says. "I thought the constituent parts all had different things to offer." In presenting Newsnight, she believes she offers a "different perspective on the world" by not being a metropolitan Londoner. "Hopefully it was an added ingredient I could bring to the job," she says smiling.

An imaginative and outgoing child, Wark immersed herself in books growing up in Kilmarnock, listened to the radio with her grandmother and took part in debate and drama (she was accepted to the RSAMD - now the Royal Conservatoire of Scotland - after finishing school, but went to the University of Edinburgh instead). Journalism appealed because she liked stories, but found the careers guidance at university "hellish". She was told that if she wanted to join the BBC - "which is what I wanted to do" - she'd need to do a postgraduate secretarial course. "And this was in 1972. It was outrageous," she says. I bet they weren't telling that to the men? "No, probably not," she laughs. When she eventually did join the corporation, in 1976, she found it "littered with over-qualified secretaries".

Luckily, Wark had ignored the secretarial instruction and, by chance, had a friend who saw a notice at St Andrews University advertising the BBC's graduate entry programme. "I applied and got in. If it hadn't been for her, I wouldn't have known anything about that programme."

At 21, she started in radio and, not long after, became a producer on Good Morning Scotland. She then spent many years in radio on various shows before moving to television, where she worked alongside broadcasting greats such as Robin Day.

If Wark has ever encountered sexism at the BBC, she's not aware of it, although, interestingly, at 28, she was the first woman to edit Reporting Scotland. "That wasn't anything particularly to be proud of," she says. "It was like, 'Why hasn't there been a woman before?' So far as I was concerned, it was only natural there should be more women involved in broadcasting."

It's a lot better today and she says, "there are more women in senior positions behind the scenes." But, she adds, "I don't think for one minute it's perfect."

While she feels being a woman in broadcasting has neither helped nor hindered her career, Wark recognises that there has been a need to show that a woman - in this case herself - can do a serious job on television. "It's about reflecting the country back to itself. Women don't just want to see men presenting programmes."

Wark says she has ridden three waves in her career: the first one being the graduate entry scheme to recruit more women; the second to recruit a wider array of UK accents; and the third to have "slightly older women on the telly".

At 58, she seems unfazed by ageing. She tries to eat healthily and plays tennis weekly. She's close to her children, Caitlin, who is in her final year studying journalism - "it wasn't anything to do with me," she insists - and James, who is studying theatre in New York. She is in touch with them daily. Her husband says she's got "the longest umbilical cord in the world".

It's a cliche, but I have to ask how Wark juggled her career and motherhood. The answer: she had a nanny for 15 years. "I could not have done what I did without trusting the person I left my kids with. If I had even the slightest doubt, that would've been a disaster."

Even so, Wark (who was pregnant during that Thatcher interview - the real reason she tried to stay so calm) remained choosy about what jobs she took on during the child-rearing years, refusing weekend working because it was sacrosanct time for her and the family. "You've just got to make a decision. And in the same way, when the children were younger, I didn't go on the hostile environment training course because I think once you've had your kids, it's hard to put yourself in that kind of harm's way. You've a different perspective."

Wark hopes to continue on Newsnight for the foreseeable future. She still gets an "adrenalin buzz" before interviews and there are plenty of people she wants to interview, such as Hillary Clinton. "I want to find out what's going on in her head."

She has also always wanted to sing in a rock 'n' roll band. "Who knows, there may be something in there for me," she laughs.

And life as a celebrity in her own right, how does she find that? "I think people in Scotland are quite catty," she admits. "I always say, we all do different jobs, I just happen to do journalism and TV. I don't go around thinking I'm a celebrity. Because you'd get slapped down in two seconds in Scotland." n