It was August 2015 when recording artist Emmi received a baffling email. It was from a man called Peter at Abbey Road Studios – arguably the most famous recording studio in the world.

She was on holiday back home in Perth, Australia, with her parents. ‘Peter said, “Here are the lyrics, record them for me and don’t show anyone.” I was on holiday so I nearly said no but he said, “Emmi, I’d politely advise you not to turn this down.”

'I got the lyrics and I noticed words like Hippogriff, Phoenix and Billywig. I Googled them and thought, “These are creatures from J.K. Rowling’s writing – whatever this is, I’m in!”’

Emmi was having friends over for pizza that night, so she hid in her bedroom to record this mysterious song, using a £50 microphone her dad had bought her. Her only brief at this stage was to be ‘jazzy and magical.’

‘I recorded it in my bedroom and I think that’s what’s gone into the movie – I never re-recorded it,’ said Emmi. ‘I sent it off, they said thanks very much and it would be nearly a year before I heard anything else about it. I worked out that it was for the movie, but we have this saying in music: “It’s not final until it’s final.” My thinking was just, if this really has J.K. Rowling attached to it, then this is the best thing that’s ever happened to me, ever. I can basically die happy now.’

That incredulity has lasted. When we met in a little café in Soho, London, Emmi was still reeling from her involvement in this project. At that point, she hadn’t yet seen movie, and said she couldn’t quite believe it until she had.

‘When I got my tickets to the premiere I was still thinking, “Is this real? I’m not going to turn up and they tell me it’s all a joke?” I’ve been keeping this job a secret for so long, and I’ve never wanted to tell a secret or keep a secret more. I thought I wasn’t good at keeping secrets, but I am. Maybe it’s just that I’ve never had a secret good enough to keep, until this.’

And, oh, what a delightful secret: to feature in Fantastic Beasts as a jazz-singing goblin. It’s a role Emmi says will particularly amuse her friends and family.

‘People don’t know I’m a goblin yet but when they find out it’ll be funny because I’ve often been compared to magical creatures,’ she said. ‘My friends will all say it’s perfect casting. I get called elf-like because I have little pokey-outy ears. People have always described me as having an “other-worldly” voice so it really is like all the stars have aligned for this job.’

Emmi beamed as she spoke about this gig; I could see how much it meant to her. And to think, she nearly passed it up to have pizza with friends in Perth. What an elusive, confusing, extraordinary experience it has been for her.

‘I’m just so happy I didn’t know much for a while because I think every part of the process would have freaked me out, if I’d known. If I’d really known that on the other end of that Skype call – listening to that take of the song, where I’m laughing and saying, “Sorry, sorry” – was J.K. Rowling and David Yates listening, I probably wouldn’t have been able to do it. Maybe it’s better not to be prepared for these things – it’s just so much bigger than you and bigger than you can imagine.’

The track ‘Blind Pig’ was written by J.K. Rowling and composer Mario Grigorov and features on the Fantastic Beasts and Where To Find Them deluxe soundtrack,, now available from Amazon and iTunes.