Katy Perry hit the studio to get over the "depression" of the US election

She said: "This was after the election and I was kind of depressed and, you know, I definitely didn’t want to write a club banger.

"I was like, 'How are we writing a club banger when the world is on fire?' and it was kind of like, it was a nice exercise of like writing a song that at first listen is a really fun song, but I guess the more you dive in to it, it has a different sub-text."

And the 32-year-old singer enjoyed teaming up with Sia on the track and praised her "best friend" for getting her through "some difficult times".

Speaking to Roman Kemp on Capital, she added: "We’ve written for the 'Prism' record before, [a song] called 'Double Rainbow', and we’ve always kind of written. I’ve known her for years, I’ve known her my whole career in the spotlight, and we’ve seen each other at all these places and gone through ups and downs.

"She’s one of my best friends and she’s helped me through some difficult times, and I was writing with my co-writer that I always write with, Max Martin, and she had never written with him and it was one of my last writing sessions and I was actually really tired because I’ve written forty songs for the record and I was just like, I’m tapped, I’m spent."

To hear Katy Perry’s first UK interview in three years in full, listen to The Capital Evening Show with Roman Kemp.