It's unusual to see the ever-ebullient Nick Nairn looking tired, but then he does have a cast-iron excuse.

It's just days before the opening of his new multi-million-pound cook school in Aberdeen, it's been a hard slog, and he's exhausted. A glance at his packed wall calendar makes you feel his pain. But this being Nairn, there's an upside: his new venture is already fully booked for its first four weeks.

"The bonkers stuff has surpassed itself in the last few weeks," he says. "But if you sit on your a**** and moan about how things are, nothing's going to change."

In 2009 Nairn was forced to postpone his planned expansion because of the economic downturn. At his cook school at Port of Menteith in Stirlingshire turnover fell by 12% from a value of £1.2 million in 2008, revenue was down 40% and he was forced to shed staff, cut back operations from seven to five days a week, and sit it out until his corporate clientele was back on track.

So, with the global economy developing a double-dip tendency, what's changed?

"The recession has, if anything, worsened since then," he concedes brightly. "But I get fed up when I can't make things happen and try to create growth. Bumping along the ground is not an option."

In typical Nairn style, he's decided to take the mountain, as it were, to Mohammed.

"The market is still there, but the idea that people from the north-east were going to take two days out of their schedule and travel to a class down here, then stay overnight, has become unrealistic. So we decided to take the cook school to the market, and in a new format," he says. "We're the first to offer bite-sized classes where you can just come in off the street, alongside the day-long classes. Being an urban setting lends itself to that kind of spontaneity."

He's done his market research. There's a buzz around Aberdeen these days, and it's nothing to do with Donald Trump – although Nairn, a former supporter of wind farms and Scotland's renewable energy programme, is now not so sure. An application for a development close to his home in Stirlingshire, where he lives with his wife Holly and children Daisy, nine, and Callum, eight, has put paid to that. "There isn't enough research into the effects on human health of subsonic vibration and sleep disruption," he says. "Though that's not to say I'm a fan of Mr Trump."

No, Aberdeen's buzz emanates from a sense of knowing where it's going, a confidence about its future. "Big companies like BP, Total and Chevron are making huge investments in the oil, renewables and construction industries. Aberdeen is an international centre of excellence when it comes to oil and gas." Coupled with that is his market of oil workers, with weeks on-shore, and their wives.

"Opening in Aberdeen is an enormous investment for me and a huge commitment given the economic climate, but it has come from a feeling of 'it's now or never'. Only recently, all of us involved sat round the table and asked, 'do we leave it, or do it?' and a show of hands was definitely a 'yes'."

The school will be run by Nairn's long-term general manager Nadine Carmichael.

"What I'm good at is ideas, concepts, promoting things and rallying people," he says. "I'm not so good at processing things; I get bored. Unlike cooking, where I love the attention to detail, with business projects it's different. Making sure 62 wine glasses are all the right size and ordered in time is not my thing. I've put people in place who can."

Nairn now works with a close and loyal team of a business development manager, a finance manager, an operations manager and a chef manager – all of whom have been with him for an average of 10 years. He will be cooking at the new school for the first few weeks, and monthly thereafter.

Nairn was Scotland's first celebrity chef. He opened Braeval Old Mill near Aberfoyle in 1986, and Nairns Restaurant with Rooms in Glasgow's west end in 1997. In 1991 he became the youngest chef in Scotland to gain a Michelin Star at age 31 – a crown he held for 16 years before being usurped by Tom Kitchin when he got his first Michelin star at the age of 29 in 2007.

Nairn's engaging personality and enthusiasm made him a natural for television, and his profile, along with his reputation as a champion of Scottish produce, was further raised by BBC's networked series Wild Harvest in 1996, followed by Wild Harvest 2 and Island Harvest, with glossy cookbooks to accompany the hugely popular series.

He closed the Glasgow restaurant in 2003, vowing in an interview with The Herald never again to run a kitchen because of the stress and long hours. Apart from running the cook school and appearing regularly on TV's Saturday Kitchen and the Scottish primetime rural affairs programme Landward, he is now "heavily involved" in his role as consultant for the Kailyard Restaurant at the Dunblane Hydro (he's just renewed his contract for a further three years) and the Vanishing Willows café at Erskine Hospital Garden Centre, as well as brand ambassador for Lidl supermarkets.

Does he harbour ambitions to return to frontline cheffing? "God, no," he bats back in a fierce knee-jerk rally. "I don't mind owning something with someone else operating it, but I'll never go back to being chef-proprietor. It's just too tough. I've done it and I've got nothing left to prove, but I just have too many other things in my life that I want to do. You can't play at being chef-proprietor, and I don't have the will to do it. I've always wanted to do different things."

Nairn was first inspired by food, travelling the world as a young merchant seaman. He joined after leaving McLaren High School in Callander at the age of 17. Life at sea also instilled in him, he says, a respect for hard work and discpline. The subject he's probably most passionate about is food education for children, and he believes the closure of home economics departments in some Scottish schools is "unbelievable".

"Schools don't want HE departments because they're expensive to run. They've let all the HE teachers go, because head teachers prefer to concentrate on league tables that are focused on achievement in English, maths and academic subjects," he says. "I would like to see the provision of food education in schools given the same weight as those other subjects, and to be part of how a school's performance is gauged. We're losing sight of our rural roots and the control of food has moved away from individuals to corporations. As a result, our children still think chips come from the van rather than from potatoes."

The 53-year-old has been a passionate supporter of the Scottish Government's national food and drink policy, and at one time was adviser to former food csar Gillian Kynoch. But he admits to going through a phase, three or four years ago, of being "disengaged" with the food scene in Scotland.

"I felt I'd been banging on about the same subject over and over and that it was going nowhere," he says.

"For a long time, I felt there was too much hot air, too much talk and not enough action. Then I was asked to speak at the Scotland Food and Drink conference in Perth earlier this year and met all these really enthusiastic people, from Government advisers to educators, campaigners, nutritionists and producers. Suddenly I switched back on. We were all in agreement about the direction food should take. We talked about how children should be able to make a pot of soup by the time they leave primary school. I've been saying that for 15 years, and finally it is being heard through the Fife Diet Food Manifesto. The mood has changed, and there's a goodwill feel about making things happen at grassroots level to really move the food agenda forward.

"As a result, I've founded Nick's Think Tank on behalf of Richard Lochhead [Food Minister] and we're all meeting here in June. Nobody will be allowed to leave until we've got a plan about how to improve food education in schools. I'm not talking about showing children a protein in a pot. I'm talking about making them feel, peel, cut and cook raw, fresh ingredients.

"Independent or not, if Scotland is going to progress in the world it has to be a nation that enjoys food, talks about food and knows how to cook it, from its youngest people to its oldest. Food is all about hand-on cooking, it's not just about theory."

And with that, he's off. Stand back, world: Nick Nairn has rediscovered his mojo.

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