Senorita writer Charli XCX turned the chart-topping hit over to Camila Cabello after realising the tune was a "better fit" for the former Fifth Harmony star.

The British popstar is credited as a songwriter on the Camila/Shawn Mendes duet, which topped the charts worldwide when it was released earlier this year.

But opening up about penning the tune during an interview with 103.3 AMP Radio in Boston on Monday, Charli admitted she knew straight away it wasn't going to be one she would release herself.

"I knew immediately the song wasn’t for me, but that it was good," she said. "This Latin Pop flare just wasn’t right for who I am because I am not a part of that culture, I’m not from there. Whereas Camila has that in her blood, so when we wrote the song we thought about her and sent it to her.”

Charli and Camila also discussed the concept of Senorita while on tour with Taylor Swift as part of her Reputation World Tour. After learning of the song idea, Camila asked if she and Shawn, her now real-life boyfriend, could have a creative input and make the song "more their own".

"We were on tour with Taylor together at the time so we were talking about it a little bit," she continued. "She wanted to do it with Shawn and they were talking about it, like it was just everyone having a long conversation about it. Obviously both of them write as well so they kind of wanted to write on the song and make it more their own."