Meeting Kirsty Wark for lunch in Glasgow involves a dawn start, the rigours of easyJet's queuing system, and a series of sustaining coffees. And by the time I make it to the restaurant, I'm feeling just a little bit fatigued. Unlike Kirsty who bounces in, shaking off the Scottish rain. But then, she lives nearby, she says, just 10 minutes around the corner.

It's only later that it transpires that she's actually travelled as far as I have. She was filming her new food panel show, A Question of Taste, in London the day before, finished late, jumped on the sleeper, arrived in Glasgow at seven, had a bowl of granola – "I make it myself but I think I put too much maple syrup in it" – then her personal trainer came round and "we were out pounding the streets at nine this morning", came back, had a shower, did some telephone interviews, and then popped along to meet me.

But then she's had years of practice. She's been presenting Newsnight for almost two decades, and having done the London to Glasgow run almost all her working life, she has her routine down pat. Do you sleep? "Oh yes. I have a whisky when I get into my bed."

She's also, I've already established, a regular at the restaurant, Crabshakk, a small but perfectly designed seafood restaurant just down the road from the Kelvingrove Art Gallery. And she ignores both the menu and the specials board and asks, "Have you got any halibut in?" He has. And after a bit of to-ing and fro-ing, between that and the scallops, she has plump, pink Scottish langoustines to start.

"Years ago, all this stuff, not the white fish, but all the other fish, and shellfish in particular, would just go abroad. I remember the lorries used to come in from Spain to Islay. Big refrigerated lorries and they just took away everything and people would only eat the white fish or herring."

Scotland still suffers, foodwise, from the "whole deep-fried Mars bar thing". Is that a misconception, then? "Totally. It was a joke! One fish and chip shop did it for fun, and then of course it gets picked up but it's never been a staple of any fish and chip shop. Italian families came into Scotland after the first and second world wars and we have these wonderful fish and chip shops and brilliant quality of haddock."

It's the kind of arcane detail that could well turn up on A Question of Taste, a food quiz which pits teams against each other, in a Countdown sort of way. (There's "Kitchen Corner", for example, as opposed to "Dictionary Corner".) And that, as a keen cook, and quite serious baker, she feels she's perfect to present.

Isn't it a classic example, I ask, of the polarisation of food? It sometimes seems that there's now a section of the population, often the middle classes, with increasingly specialist food knowledge – and then everyone else, who shops at Iceland. "I absolutely don't think it's right, this assumption that only middle-class people cook very well. And I will tell you why that is not the case – because of the profile of the people that spoke to me after MasterChef. Guys at petrol stations coming up to say, 'I am glad you cooked that the other night.'"

Ah, yes, MasterChef. Wark was on the celebrity version earlier this year and loved it. She got through to the final round, with a menu of sorrel soup with salmon and dill, served with oatcakes; a main of calves' liver with Swiss chard, rosemary and garlic chips and mustard mayonnaise; and pistachio meringues with rose cream and rose and cardamom panna cotta. The meringues were a triumph but Gregg Wallace declared the liver "furry" and Phil Vickery (the rugby player rather than the chef) went on to win.

Are you still haunted by things you should have done differently?

"Completely. What really pissed me off is when I was doing raspberry creme brulée. And you can only make that if your raspberries are really fresh. If they are sitting then they become acidic and soft and then it infuses the creme brulée and makes it curdle. If I'd just looked at the raspberries a little longer I would have realised… it's just one of life's little…"

And she shakes her head. She's a hugely keen cook, so going on MasterChef was quite a big deal. Newsnight had to work around her schedule for four months. ("But then, loads of people at Newsnight are completely obsessed by MasterChef.") And she wanted to win. "The ignominy of going out in the first round would have just been too hard to live with."

Mostly, though, cooking is her way of relaxing. Does she worry that playing the domestic goddess is in some ways anti-feminist? That this whole 1950s return-to-basics trend is about putting women back in the kitchen?

"I think men are in the kitchen now, too. I thought about this a lot because if I had been offered MasterChef when I was much younger would I have done it? Would I have done it back then, or would I have worried that it would undermine my credibility? Wrongly of course, because I have always cooked and I have always baked in the privacy of my own home, but the danger is that you would be typecast."

She wouldn't do Strictly Come Dancing, she says, and she makes a face when I mention the annual mini-skirted newsreaders' sketch for Children in Need. Although I think that she has the gravitas to rise above whatever vehicle she's in.

What isn't clear is if she'd get the break now. I tell her how I watched novelist Clemency Burton-Hill stand in for her on The Review Show a few weeks ago, and I couldn't help being struck by the fact that both she and Newsnight presenter Emily Maitlis are intelligent and accomplished, but both just happen to look like models.

"You can't blame them for that."

"You can't," I say. "But you can blame whoever is putting them there."

"I get criticised. I get called 'the older woman'. Hello? Does that mean that my brain cells are completely atrophied? It's one reason why I always keep trying to be better. To be there because you're good at it, not just because you've been there a long time."

She does get criticised. The Mail writes of her "smug superiority" and likes to point out when she wears a skirt it thinks is too short. ("It was a knee-length dress. It rode up. Hello?") And in 2005, the press took delight in learning that Scotland's then first minister, Jack McConnell, and his family had holidayed at Wark's Majorcan villa.

In the flesh, though, there's really not much evidence of smug superiority. Television has made her rich (as well as her Newsnight salary, she and her husband pocketed a million or so each from the sale of their TV production company a few years back), but she's approachable and tried to insist that I come back to her house instead of hanging out in the Glasgow rain.

Mostly, though, she still absolutely loves what she does. And there's a touch of the lioness about the way she defends Newsnight. It's nonsense, she says, to say that it has gone off the boil, as some recent headlines have suggested. It's better than ever, in her opinion, and she tries harder than she ever has. She loves doing "homework", she says, mastering the detail, learning the brief. "If I didn't, I'd be terrified."

It seems impossible to think of Kirsty Wark being anything but unflappably competent. "But if I'm interviewing the prime minister I still have to have his name in front of me. Just in case." Really? "Oh yes. I have to. I'd be scared shitless otherwise."

A Question of Taste starts on Monday 2 January at 8.30pm on BBC2