When Annabel Williams was 19, she was holding jazz workshops in the prop room of a theatre in west London.
One day, a quiet 16-year-old walked in. That teenage girl would go on to be one of the greatest British singers of all time - it was Amy Winehouse.
Annabel coached her for her first ever "insanely good" live performance in a tiny pub, which she got paid a tenner for.
From there, she went on to become of UK's the most in-demand vocal coaches.
Annabel has since spent 10 years working on the X Factor, Britain's Got Talent and even performed at this year's Eurovision.
"We would sing and listen to Dinah Washington and Ella Fitzgerald," Annabel recalls, thinking back to her time coaching Amy Winehouse.
"Amy loved those singers and that really connected us, but I didn't get a lot from her if I am honest."
Annabel says Amy was quiet and wasn't always sure if she was even listening to her in class.
"She was just a normal 16-year-old, she had a thick head of curly black hair and no tattoos," she adds.
"I remember teaching her a song she was going to perform for her first ever gig and again, I was never really sure whether she was listening to me.
"But then when she went out and sang with the band and I remember, we were all thinking, 'Oh my God, she's insane'.
"And she actually said years later in an interview, 'Well, my first ever gig was in an old pub in front of a load of old people'.
"I'm so proud, I was there and I think after the one thing, it just blew up."
Ten years ago, Annabel started working on the X Factor as a vocal coach and says it changed her life.
Her first year saw her train the likes of Ella Henderson, Rylan and eventual winner, James Arthur.
"I was so nervous to start with," she says.
"I was put in this room with executive producers and cameramen, sound people, cameras everywhere, James walks in and it is all on me to lead the session.
"James was happy to be left doing his own thing so I had to get the right balance of not being too overbearing but needing him to listen to me because I had something to prove on my first day."
And that is an interesting dynamic Annabel faces with her famous clients.
"I'm in charge and normally they are in charge, so it's my job to keep their attention," she explains.
"I have to get an instant result, I'm not often in a situation where there is a show in six months - it's more like that very night.
"So I've had to develop a way of getting results instantly."
She was once asked to warm up Katy Perry in 17 minutes before an X Factor performance, and she had never met the pop star before.
"I went to her Winnebago and she's completely surrounded by people about to do her hair and make-up," she explains.
"We had to do it right there, she has got a hell of a voice on her and that is not easy to warm up quickly.
"She was fantastic, she listened to everything I said, kept her concentration and off she went."
The pandemic put a stop to some of Annabel's work like X Factor and Britain's Got Talent, but it opened another door - Eurovision.
She was James Newman's vocal coach and one of his backing singers.
They trained for about three months to prepare James for performing in front of a worldwide audience of 200 million.
"On the night it was hysterical because I wasn't allowed on stage," she explains.
"They built a little blacked-out booth with no monitor in it, so I couldn't actually see the performance when I was singing.
"Then the song was over and I heard the roar of the crowd and then we could party. Despite the result, we had a great time. James couldn't have worked any harder."
With Annabel's years of experience, she now reckons she can help anyone sing.
She has developed an app called The Vocal Coach which she says can train you to sing like a professional.
"If you can speak, you can sing," she claims. "Even if you are terrible, you will improve and I have developed these exercises from years of vocal coaching on television shows, why not make them available to everyone else?
"I can teach anybody how to sing. And then whether that end result is any good? Who am I to judge?
But there is one person she still wants to get her hands on.
"Mariah, because she needs me," Annabel laughs. She has been one of my favourite singers since I was 11. And I always put these things out in the universe. You know, I did it with X Factor.
"I just would love to know what's going on with her with her chords and just help her get back into a routine.
"I mean, I think she's one of the best pop singers that ever lived. You know, she's just the most perfect pop singer."