“SURE, it’s a man’s world, but here I am, right in the middle of it! Ha!”

Cecilia Bartoli is backstage at the Festival Theatre in Edinburgh, gesticulating so abundantly that her arms keep nearly bashing the walls. She’s a compact woman but this dressing room is nowhere near big enough for La Bartoli.

The opera singer and Salzburg Whitsun festival director has just held a press conference about her role in Bellini’s Norma, which opens tonight at the Edinburgh International Festival, and the scheduled ten-minute Q&A ended up a roaming 45 minute discussion of period instruments and bel canto pitch politics. Did you know that Giuseppe Verdi tried to have it enshrined in the Italian constitution that orchestras would forever play at A=430? I didn’t.

Before the press conference, Bartoli held a photo call in the foyer of the Festival Theatre and was totally in control of the sizeable pack of cameramen vying for her gaze. At 50 she has done this a few times before, and she expertly propped herself against the banister: slick suit, big heels, big hair, big eyes. Bartoli is among the last of the world’s opera divas. If that category seems like it should belong to bygone centuries, Bartoli lives and breathes and fuels it with zero apology.

At the press conference she was flanked by four men in suits, with EIF director Fergus Linehan and conductor Diego Fasolis to her right and Norma directors Moshe Leiser and Patrice Caurier to her left. There was no question who was in the driving seat. Bartoli fielded the questions, Bartoli provided the drama. She’s good at this: her answers were emotional and funny and focused, as though she had never before been asked about what date the production premiered (2013) or whether it’s her first time performing in Edinburgh (it is). And when she stepped in to translate for Fasolis, who shyly joked that his mother was an English teacher then switched into understated Italian, her English versions were notably more punctuated with grand gestures and rhetorical pauses. For Bartoli, performing is performing: this, too, is how she sings.

Now she’s running late. She is due to be on stage rehearsing in approximately two minutes’ time, but to her assistant’s consternation she’s still talking to me – in fact, she’s still in full flow of conversation. “I couldn’t believe it when they offered me the Salzburg job!” she is recounting. “I mean, my predecessor was Maestro Muti! Of course I was the first woman, and about a hundred years younger than the others… So I decided that I would feature a whole bunch of strong female characters in my programmes. Cleopatra, Norma, Cinderella…”

“This year we did West Side Story with Gustavo Dudamel and the Simon Bolivar Symphony Orchestra, which was the first time there has ever been a musical in Salzburg. Can you imagine it? A piece of musical theatre in” – she draws an exaggerated breath and makes big quotation marks in the air – “The Temple Of Classical Music?! It was pretty major! And it was such a success that we had to add extra performances, which is totally new in the history of the festival, and which allowed us to bring in new audiences, and which is absolutely what we need.”

She laughs. “That kind of shake-up can be done by a woman! I have proved that it can!” Her contract at Salzburg was recently extended until 2021.

Thing is, Bartoli has called the tune since long before she got that job in Salzburg. “I was always extremely careful with my voice,” she told the Edinburgh press conference. “I made my choices so that I can still be singing today. I only do things when they feel right.” Along the way she convinced agents, opera houses and record companies to get on board, releasing albums full of obscure baroque arias or whole collections of Salieri – hardly be the dream stuff of major label bosses.

And now Norma. The main reason Bartoli’s version is billed as "radical" is that Bellini’s title role is normally sung by a soprano – powerhouse voices like Maria Callas, Joan Sutherland and Montserrat Caballe defined the role in the 20th century – and strictly speaking Bartoli is a mezzo-soprano, and a rather light one at that. Or at least, she was. Now her biography tends not to specify mezzo or otherwise. Her reasoning is that back in the 1830s, when Norma first premiered in Milan, there was less distinction between voices, and anyway, the original Norma was Giuditta Pasta, who also sang Tancredi and Cenerentola and other roles now associated with mezzos. (Cenerentola is a classic Bartoli role: her rendition is almost hysterically bright and bubbly).

So by using a new edition of the score, by removing all standard cuts and restoring all repeats, by employing an orchestra of period instruments (I Barocchisti from Lugano), Bartoli pitches her Norma as bel canto authenticity.

“Bellini never met Puccini, he never met Verdi,” she says. “He was closer to Mozart, he was a contemporary of Schubert. His singers grew up singing Handel. So why does everyone perform him like he was writing Verismo?” She points out that “although women haven’t changed much since 1830, orchestras sure have. Why do they have to play so loud nowadays?” She turns and beams at Fasolis. “Actually, they don’t have to!”

And if there have been smirks from the opera world about Bartoli’s normal strategy allowing her to dodge critical comparison – she sings dusty corners of the repertoire, she appears in very few staged operas – well, with Norma she invites direct comparison with some of the ultimate voices of the 20th century.

Does it bother her, I ask, that people will forever bring up Callas and Sutherland? “Not at all!” she exclaims. “The reason we can do this version is precisely because of the great divas of the past. Listening to their interpretations was a great inspiration for all of us, but now we can get closer to the composer. In the end it is Bellini’s Norma. Three years ago we released the first ever complete recording with no cuts. It was a premiere! In 2013! Which sounds a little bit weird right?” She grins. “Well, weird is great!”

Cecilia Bartoli sings Norma at the Festival Theatre, Edinburgh, tonight, Sunday and Tuesday