I'm not bothered about titles. If the buck stops with you, the buck stops regardless of what people call you

Otherwise the whole thing could go into meltdown? Well, yes. In 2008 an embarrassing box office ticket fiasco resulted in a 10% drop in sales. But since the 43-year-old Orcadian came on board in 2009 the Fringe has stabilised, last year selling a record-breaking 1.8 million tickets. And this year it's bigger than ever, with a 6% rise in the size of its programme. Is she a stats and figures person?

"Oh yeah, I love spreadsheets," she laughs. Thanks to her background in accounting? "Maybe," she nods. (Mainland studied English literature at Glasgow University before doing a diploma in accounting at Strathclyde University.) "Or maybe it's the control freakery again. The Fringe is too big to envisage so maybe that's how I make sense of it."

When the Fringe launched in 1947 it comprised eight theatre groups. This year it will have 22,457 performers doing 42,096 shows in 279 venues. How does it keep getting bigger? "I don't know," she replies. "Magic?"

There is something remarkably special about a festival that attracts such diverse performers from every corner of the globe. "But it's not the fact of being bigger," adds Mainland. "What's important is that people still see it as a valuable place to bring work. For us, that's what's important."

Today we're taking tea at Edinburgh's Hotel Missoni. One imagines it's a welcome break for Mainland, who admits she works "too many hours" – albeit happily – but this part of the role, the "media" bit, is her least favourite. Despite a varied career on the Edinburgh arts scene – first working for the Fringe in 1991 before becoming a freelance festivals and events producer and, finally, acting as administration director at the Edinburgh International Book Festival – Mainland had never been a "figurehead".

"And I didn't want to do it. That bit didn't appeal to me," she says.

If she's honest, it's the reason she didn't apply for the role earlier. "But now I think it's an important part of the job, the rest of which I really love," she laughs.

And she's good at it. Articulate, calm and passionate – Mainland is all these things but her forte, she says, is being organised – and tenacious. "And I hope I'm pretty easy to get on with."

She credits this latter quality to growing up in Orkney where "you're surrounded by a whole community of people who know who you are. You have to get on with everybody. If you don't, you're stuffed. There's something about that – dealing with all kinds of people – that translates to this role".

They know of her success at home: "But in that lovely Orcadian way, they're not fussed about it."

It's that down-to-earth mentality and strong work ethic that has contributed to Mainland's success in the role to date. "It sounds cheesy," she says, "but I fundamentally enjoy the festival as a punter. In the last three years I have genuinely seen some of the best things ever."

Last year she found herself in a small, nondescript venue, doubled-over laughing. "There's nothing like sitting in a tiny, hot venue with other people being completely excited. That's satisfying."

Mainland always wanted to work in the arts but never had a career plan – "I just fall into things" – but says she knew she didn't want to be doing something creative herself.

"I'm admiring of people who are writing or standing on stage, but I've always been interested in backstage, in its broadest sense. The idea that those people need others to put them in front of an audience, whether they think it or not," she laughs.

Part of her role is wrestling with strong-willed creative types. "And I love that. At the Fringe, there are millions of them. I think it's fascinating because my brain doesn't work like that."

Her role, she says, is to facilitate and support the Fringe – which is non-programmed and open to all – not to direct it. It's the reason her title was changed from director to chief executive officer. "I dropped the officer, that's too many words."

Still, it implies that if it all goes wrong, it falls on Mainland. "Yes," she agrees nervously. "But I'm not really bothered about titles. If the buck stops with you, the buck stops regardless of what people call you."

Nevertheless, it must have been daunting taking on the position at such a precarious time? She hesitates. "Well, I applied knowing what had happened in 2008. If you're worried about something and you think you can help, then you should stand up for it."

Not to blow her own trumpet, Mainland believes her organisational skills were exactly what the Fringe needed. "It's presumably why they gave me the job because, essentially, I'm an administrator. And I have a good understanding of the Fringe. It's a complicated beast. Trying to see the whole picture, that's a difficult thing for somebody to come in and understand, particularly at a time when you're also trying to sort the organisation out. At that point I was a good person to do it because, in a sense, I grew up with the Fringe."

She admits her first year on board – having started in April, late in the festival year, alongside a whole new team – was a bit "seat of the pants".

"But we just got on with it," she says with typical pragmatism. "It was a complete whirlwind – which is what it's always like – but I enjoyed being back. Although now, I don't know how we did it."

With year one over, Mainland could breathe a sigh of relief. "I never thought I made the wrong decision [taking the role], which is good, because you never know. And I never thought, 'That went well, we've done it.' Anyone who works in festivals will tell you, the minute one finishes, you start thinking about the next. What worked, what didn't and how are we going to top it next year?"

Did she ever sit back, overwhelmed that she was the one running the whole thing? She laughs at this. Then, says: "I don't know if this makes it worse or better but I never think I'm running it. Because we're not running it. We're holding it."

Despite starting her career at the Fringe, this is a role she never envisaged doing. Is she ambitious? "I don't think I am at all, but I said that to a friend and they said, 'That's ridiculous, of course you are.'"

This year will be Mainland's fourth Fringe. "So I can't really say I'm new any more," she says. "And in some ways, the next three or four years will be as interesting as the first few. It was quite obvious what needed to be done in 2009. Now it's about continuing a forward trajectory."

But Mainland loves it. So much so that, come August, when the festival is underway, rather than relax, she's out and about. "Why wouldn't I be? Even if I try really hard, I'm only going to see a tiny percentage of the shows and meet a tiny percentage of the people. It's our only chance to take the temperature of it. I'm always asking people, 'What did you see?' And then we collapse in September."

Mainland previously worked under Catherine Lockerbie at Edinburgh Book Festival, who was forced to take time off from running it because, in her own words, she was working "too hard, for too long". Did Mainland take any lessons from Lockerbie's experience? She'd rather not answer – it was, after all, personal to her; but she concedes, how she deals with a work-life balance is a good question.

"We shut at Christmas – two weeks on the sofa in your pyjamas, with The Killing to watch, that's how you get your life balance."

She admits she doesn't sleep well and finds it hard to find "that switch that you turn off". Thankfully her boyfriend – "I've been with him for 10 years so boyfriend sounds a bit weird" – works in the entertainment industry so he understands, she says.

As for the future: "Something will come up that is right. But not at the moment.

"Ultimately, I'd go to somewhere really tiny," she laughs. "Maybe I'll go and run the smallest theatre in the world. With one performance every 10 years ..."

The Edinburgh Festival Fringe is on from August 3-27. Visit www.edfringe.com.

Kath Mainland chief executive of Edinburgh Fringe