CATRIONA Morison is trying to decide which of the many costumes she has worn on stage was the maddest. “Oh gosh, I have two that spring to mind,” the mezzo soprano tells me. “One was an angel in The Tales of Hoffmann. I had a wing on one arm and a long flowing dress. I had a bald cap on, I was painted grey and I had a prosthetic silicon breast piece. And I was tied to a chair.”

It took an hour to put the bald cap on alone, she says. You should have just gone method and shaved your hair off, I suggest. “Oh gosh, no. I don’t think I could do that. Although, apparently, it suits me …

“And the other costume I had was for playing a princess in The Love for Three Oranges by Prokofiev. But I was not a very good princess. I had black teeth. I was a showgirl, basically, so I had this big feather puffy ball on my head, a massive feather boa, sparkly dancing shoes and a glorified bikini. That was crazy.”

Admit it, Catriona. This is why you got into opera, in the first place, isn’t it? It’s just a better class of dressing up. “Exactly,” she says, laughing.

It’s a Tuesday morning at the start of May and Catriona Morison, once of Edinburgh but based these days in Germany, is sitting in her flat in Wuppertal on her day off. The sun is pouring into her living room and things are good, as long as she can ignore the mess that surrounds her.

“I’ve been working in Cologne. I’ve not been at home for about three weeks. I have a suitcase that is half unpacked. I have some admin to do and I should probably do a bit of dusting. I think Netflix will be on in the background.”

That’s for later, though. Right now, she is talking to me about the past and the future. She can see the sun shining in both directions these days. This month Morison returns to her home city for an appearance at the Edinburgh International Festival, singing songs by Brahms, Schumann and Mahler. “I’m really so excited,” she admits

And when she comes back she will be bearing the title "BBC Cardiff Singer of the World,” which she won last June, all the more impressive as she was a wildcard entry to the final. She was the first British winner of the title. A deserved one, too. Her take on Dido’s Lament by Henry Purcell that night was a thing of beauty; sonorous and deeply affecting.

Morison still sounds a bit stunned by her success. “It’s such a blur. I was so swept up in the moment and swept along with everything that it’s all a bit surreal.”

“It’s certainly accelerated my career, which is wonderful. And in Britain I’m now more known than I was. I wasn’t very well known in Britain because I hadn’t really worked much there. After I graduated I came over to Germany.”

She’s been in Germany for four years now, spending the last two seasons in the ensemble of Oper Wuppertal. What percentage German is she now then? “As a person? I’m 100 per cent Scottish!”

She sounds a bit horrified at the question. Come on, though, Catriona. There’s no German-ness sneaking in at the edges? “When I speak sometimes I use German grammar and it comes out very odd,” she concedes.

There is, too, a slight Deutsche dusting to her accent these days. When she mentions that performance in Offenbach’s The Tales of Hoffmann, her most recent role, her pronunciation of “Hoffmann” has a real Teutonic snap to it.

Otherwise, she is a well-spoken, polite (it’s always “gosh” and “goodness”, never anything stronger) young woman just tiptoeing into her thirties. No diva tendencies, Catriona? “I’m a mezzo not a soprano,” she points out.

Morison grew up in Edinburgh in a house where music was always being played. Her mum gave piano lessons and Morison herself studied violin and viola. “I thought I was going to be an orchestral musician.”

But she would always sing around the house and it came naturally to her. “I think everyone has a voice. Everyone can sing. It’s just how we use it.”

You clearly haven’t heard me sing, Catriona, I tell her. “But it’s in there. And I think whether you sing in the shower at home or whether you go and sing at karaoke it’s something that is very accessible.”

There is, she accepts, a little more to singing an aria than bellowing out Dancing Queen down the local though. Consistency of range, singing in other languages, singing duets and in an ensemble and knowing “where you need to be to bring it out and where you have to let your colleagues blossom.”

Then there’s stagecraft and acting, as well as the sheer stamina needed to get through a performance. Is she a gym bunny? “Some singers are. Some singers go out for runs on the day of a show. I think if I did that I would exhaust myself. I prefer to conserve my energy and give everything on stage.”

She does eat a lot of bananas, though. That’s the opera diet.

Here’s what I want to know, I tell her. Opera is about extreme emotions – passion and jealousy and wrath and all of that. How do you tap into such things? Do you have to have had your heart broken to sing about heartbreak?

“I don’t think so. There’s always a way to access something even if you have no experience of it. It’s understanding what the character has come from.”

She once played Maddalena in Verdi’s Rigoletto, Morison points out, which involved her playing Russian Roulette with a (thankfully fake) gun. She didn’t need to feel suicidal to play the scene. “You find other ways of tapping into what scares you in life.”

Morison traces her singing career back to studying at the Royal Conservatoire (then the RSAMD) in Glasgow. She was still studying the violin at the time, but when she had to work on a group instrument she opted to sing duets with another girl in the class and a teacher subsequently offered to give her lessons every week.

The memory of it prompts an urgency in her answers. “Music in schools is so important and without having him in school as a singing teacher with all his qualifications and knowledge it would have been a very different journey for me. Having that access at school was so important.”

And music is under pressure in Scotland now due to school cuts. “It is! It is! And it’s so disappointing to see. Music is so important for everybody in the world. It’s all around us everywhere: in films and TV and adverts, your doorbell tune, your ringtone. It’s everywhere.”

What are we in danger of losing? “A new generation of musicians. You don’t know where they are going to come from.”

In Germany, she reckons, music is simply a much more integral part of society. “There’s basically an opera house in every city, more or less. Compare that to the UK and it’s worlds apart.

“I think if there was a different opera house in every city in the UK it would be a different story because every opera house would be able to do outreach programmes.

“It’s a very normal thing to go into a theatre as a child over here with your school class and that is achievable because here in Wuppertal we have a theatre and in Edinburgh if Scottish Opera isn’t playing at the time then you just don’t have that chance which is a big shame.”

Let’s end on a high note. What will playing the Edinburgh Festival mean to you, Catriona? “Everything. Oh, my goodness. Coming from Edinburgh I was so lucky to have access to all these wonderful concerts, wonderful artists, singers, instrumentalists, orchestras, you name it.

“And now to be on the other end it’s really a dream come true.”

Whether she will be wearing wings or a glorified bikini we will just have to wait and see.

Catriona Morison is in recital with pianist Simon Lepper at the Queen’s Hall in Edinburgh on August 15 at 11am.