WHEN Holly Mathieson makes her debut as assistant conductor of the Royal Scottish National Orchestra this weekend, she will probably be dressed as a fox. Possibly as a cat. Mathieson conducts the orchestra’s Halloween concerts and has agreed to do so in full costume — “I did wonder whether it’s something all new assistant conductors have to go through as some kind of initiation ploy,” she ponders, “or whether the orchestra just hit the jackpot with me.” Hit the jackpot? “The fact that I got so excited about wearing a bushy tail.” Does she care either way? “Nah,” she grins. “I mean, bushy tail! And my priority here is making it magic for the kids. It’s not about me.”

Mathieson is a 35-year-old New Zealander whom I meet the morning after she moves to Glasgow. She arrives for the interview with her husband, Jon Hargreaves, an affable conductor and arranger from Leicester. (The pair met as conducting fellows at Dartington Summer School in Devon, where Mathieson jokes “you either get engaged or get pregnant”.) And though it’s been less than 24 hours since she moved to Glasgow proper, Mathieson isn’t new to the city: she is already resident conductor of the National Youth Orchestra of Scotland’s Junior Orchestra and she was Leverhulme Conducting Fellow at the Royal Conservatoire of Scotland.

Neither is the fox thing just an aside. Mathieson is perfectly aware of what it means to craft the right image and identity on the conducting podium, not least because she holds a doctorate in Music Iconography and wrote a thesis called "Embodying Music: The Visuality of Three Iconic Conductors in London, 1840-1940". Basically she spent several years looking at portraits and written descriptions of stern Victorian gentlemen with extravagant whiskers. Not a single woman cropped up in her research, of course, and certainly no fox outfits.

As she’s talking about her iconography studies I recall that, when the orchestra sent me through her own official headshots to accompany this article, I was struck by how relaxed and personal the photographs are. There she is: smiling, friendly, fun, which is much like she is in real life and not very much like the usual photographic statements of authority and genius and pedigree. “Yup,” she nods. “Classical music iconography hasn’t changed all that much since the 19th century. Most conductors want to make themselves look more successful than they really are, and I often look at pictures of my colleagues, both men and women, and wonder why on earth they’re all pretending to be middle aged men.”

She tells me about one agent who remarked that at some point a young conductor need to stop getting portraits done that make them look like "good assistants" – which is to say hard-working, earnest, enthusiastic, puppyish. “That’s why most conductors in their 30s end up commissioning photos that make them look like the boss. And looking like the boss means looking like a 60-year-old man.”

Several factors set Mathieson apart. She comes from the Antipodes, for starters, and she says she has already found it useful to be an outsider to UK’s class and gender attitudes. “I left school with a female head of department, a female university vice chancellor, a female Prime Minister. We took it for granted we could go as far as we wanted as long as we had the talent and work ethic to take us there.” It is notable that New Zealand’s three most most successful under-40 conductors today are all women – that’s Mathieson, Tianyi Lu and Gemma New.

Mathieson and Hargreaves also share a joke about the stereotype of New Zealand woman as “ball-breaking, assertive, to the point, controlling”. Funny, I suggest, how those are all attributes that might have applied to those 19th century whiskered gentleman conductors. “Right!” Mathieson laughs. “It’s because the European settlers went to New Zealand in the middle of the 19th century and shortly after that all the men went to war. So there was this bunch of Scottish and Dutch women who just had to get on with clearing the bracken and setting up the farms. To survive that journey, probably pregnant and giving birth along the way, they had to be pretty damn hardy.”

Mathieson seems pretty damn hardy herself. When she moved to London she worked as librarian for the Philharmonia, a job that required 80-plus hours a week of hard graft. “No career path, no photocopier, no computer system. I guess you were just expected to slog it out until you become an alcoholic and died. It was a tough two years. I had a brush with cancer, I got a lot of grey hairs, my major relationship broke up, I lost a lot of weight. But ultimately I found it exhilarating.”

What made it exhilarating was mostly the proximity she had to the Philharmonia’s top conductors, particularly Esa-Pekka Salonen. “I got on really well with him. One of my unwritten jobs was to tell him filthy jokes in the wings and make him giggle before he walked on stage. I would tease him about being short, that kind of thing. I’d take the piss out of him quite mercilessly and I think he appreciated that.” As librarian, she says, “You’re the only person who doesn’t need to call the conductor ‘maestro’. They know you’re the musician on staff and they treat you differently. As librarian you’re the person to whom they come off stage and whisper, 'I really screwed up the third movement, didn’t I?’”

I doubt every librarian earns conductors’ confessionals to quite such an extent, nor shapes the job into such a high-level apprenticeship. Mathieson ended up assisting Salonen, Christoph von Dohnányi and Marin Alsop, the latter during the period of her historic Last Night of the Proms when she became the first woman to lead the iconic event. Alsop found herself once again positioned as the spokesperson for women on the podium.

“I suspect she has accepted that she’s the woman conductor who answers that big question so the rest of us don’t have to,” says Mathieson. Susanna Mälkki, for example, declines to discuss the subject of gender. “I think because she believes it’s prolonging the issue. I’m probably more similar to her way of thinking, but Marin is of the generation who had to cut through a whole lot of crap. For me, the issue is now about power imbalance in the industry for both men and women.” She adds that if she has ever faced attitude problems from orchestral players, it has usually been from older female musicians who “don’t like seeing a woman on the podium”.

In general, though, Mathieson says she feels “incredibly lucky to be living in an age when people are interested in perceived feminine qualities in leaders, whether men or women."

"The job is more collaborative, more sociable. Most musicians – not all, but most – no longer want that old-school authoritative figure of the Victorian portraits.” Bring on the fox costumes.

Holly Mathieson conducts the RSNO Children's Classic Concerts on Saturday at the Glasgow Royal Concert Hall and Sunday at the Usher Hall, Edinburgh