When the chef and cookery writer began her hotel career, the produce on offer was a long way from the fresh and varied selection available now.

When Claire Catlow of Cumbria married Highlander Godfrey Macdonald at the age of 20 in 1969, she was to be catapulted into a life of titled privilege on his 45,000-acre family estate in Sleat on the Isle of Skye.

Well, not exactly. When her father-in-law Alasdair died suddenly aged 61 in 1970, Godfrey not only inherited the title Lord Macdonald of Macdonald, but became the 35th High Chief of Clan Donald, one of the largest of all the Highland clans.

He also inherited four crumbling hotels and massive double death duties from his father and grandfather. Years of tough times and disappointment followed as the couple faced selling the entire estate to pay the debt, controversially set up the Clan Donald Lands Trust to secure it, were forced to sell half the estate and one hotel to finally settle the debt, then had to confront Godfrey's alcoholism.

After all that, you can only admire the couple's determination and sheer hard graft in building up Kinloch Lodge to become the internationally renowned hotel it is 40 years on, complete with a Michelin-starred restaurant and a place in a Conde Naste list of the world's top 25 small hotels.

Oh, and she also managed to carve out a career as a cook, food writer and cookery demonstrator and bring up four children. At the age of 64 she has five grandchildren and counting, and although she and Godfrey have moved to the Black Isle, she continues to promote the best of Scottish produce.

I'm exhausted just listing her achievements, but when we meet up in Glasgow ahead of the publication of her memoir, she looks fresh and youthful – the combined result of a recent holiday and having lost a stone since March with the Dingwall branch of WeightWatchers.

"When we took over Kinloch Lodge in 1970, it had been running as a hotel since 1952 but had an occupancy rate of 20% and was making a gross loss," she begins. "Our first Christmas there was the most miserable five days imaginable."

In their first year, they got through 34 workers out of a tiny staff – a harsh lesson, she says, in people management.

Then, Scottish hospitality was a very different business. "I wanted to make food using Scottish seasonal produce but it proved very difficult. We had a fruit and veg delivery every two weeks during the season, from May to September. It was impossible to buy a tomato in a tin, never mind a fresh one. At the beginning we had to rely on frozen vegetables."

Although not a trained cook, Lady Claire managed to create a menu of "dinner party-type food" based on her collection of Cordon Bleu magazines. Herb scones with pea and mint soup, prawn and chicken mousse, eggs nicoise, canapes with Scottish roast beef and smoked fish pate were among the dishes she created in the 1970s.

Even as recently as the early 1980s, recipes using freshly ground black pepper and fresh garlic were deemed "elitist" by the editor of a vegetable recipe book she was commissioned to write for the Asda supermarket chain.

She and Godfrey voted SNP in the 2007 and 2011 Scottish elections because of their admiration for Alex Salmond and the SNP's focus on attracting investment in the Highlands. She is especially proud of the Scottish Government's first national food and drink policy, launched in 2007 with the aim of increasing Scottish food sales from £7.5 billion to £10bn by 2017.

"Scotland is an exciting country and several people have remarked to us how it feels as if it has more pride and confidence. I give the SNP full credit for this," she says. "Richard Lochhead [cabinet secretary for rural affairs] has done so much to raise the profile of Scottish produce and increase food exports, and works tirelessly on behalf of farmers, fishermen and local food producers.

"Food has changed tremendously on Skye. Like the rest of Scotland, there's a great pride in local produce. We can get fresh herbs and salad leaves from three growers, and the Co-op in Broadford buys from local producers. There's an excellent dairy section there, and a very good farmers' market in Broadford. And the Spar at Ardvasar is fantastic."

However, she is frustrated by a persistent negative attitude in some parts. Her reaction to the news that the menu at the first Olympic event at Hampden in Glasgow meant visitors were offered mince, steak, curry or cheesy bean pies, crisps, chocolate or fizzy drinks, was unequivocal.

"What a missed opportunity to showcase our gorgeous fresh strawberries, our fantastic dairy produce, our prime beef," she says, adding: "I believe the rest of the world begrudges giving Scotland praise for its wonderful natural larder. It's mocked by countries such as Germany, where they are knee-deep in dumplings and think good food comes out of a lake.

"I don't have any Scots blood, I'm a brash Lancastrian with a dash of Geordie, so perhaps that makes me able to say this: the Scots have this hugely attractive character fault, an innate modesty, which stops them from boasting about how good their food is. Nobody says enough about it. By contrast the Irish are happy to tell everyone that the best food in the world is theirs, which isn't true."

This modesty springs from the fact that many successful Scottish food businesses are family-owned, which can lead to looking inwards instead of outwards, she says. "When the older generation hangs on too long it can inhibit fresh input from younger members of the family." Taking her own advice, she and Godfrey – who both converted to Catholicism in the early 1980s – moved to the Black Isle in 2009, passing responsibility for running Kinloch Lodge to their daughter Isabella and her husband Tom Eveling, under head chef Marcello Tully. After gaining its first Michelin star, the new management swapped carpets for heated floor tiles in the bathrooms and installed a small spa – something Claire would not have dared do, though she concedes that "glitzy" bathrooms are now de rigueur.

Asked to identify the greatest challenge for those involved in hospitality, her immediate response is 20% VAT (she wants it reduced to at least 10%) followed closely by TripAdvisor, the online review site written by travellers, which she wants abolished.

"TripAdvisor relies entirely on input from the public – at least, that is its stated aim. But it can be hideously abused because it permits anonymity and is unable to police the reviews, so it can license outpourings of bile from people who have never spent a night in, eaten at or visited the establishments.

"We have been threatened by one guest who asked for a discount, was refused, and then told us to wait and see what they wrote on TripAdvisor.

"It only encourages that horrible streak in people. I'd say 99% of people are very nice, but the remaining 1% can be stinkers."

And with her dazzling smile, she links arms with her darling Godfrey, and is off.

Lifting The Lid: A Life At Kinloch Lodge, Skye, by Claire Macdonald, is published by Birlinn on Tuesday, priced £17.99.