Kelsea Ballerini on disco balls, ugly tears and stolen luggage

The singer moved to Nashville aged 15 and broke records with her debut album

"I think I could fit my whole band in there," says Kelsea Ballerini, raising her eyes towards Europe's largest glitter ball, which is suspended from the ceiling of a hotel in central London.

"Think about it: We could roll from show to show like hamsters."

The country star is sizing up the mirrored monstrosity just an hour before she performs directly beneath it for fans and the press.

Although it's an acoustic set, the breadth of Ballerini's songwriting is apparent: the 26-year-old, who's the only female artist to have topped the US country charts with her first three singles, mixes the Nashville twang of Peter Pan with the crossover pop of Miss Me More and the syncopated strut of her Chainsmokers collaboration This Feeling.

But the highlight is her new single Homecoming Queen - a simple, heartfelt ballad about facing up to low self-esteem.

In the song's video, Ballerini is seen walking off stage full of confidence, her ears ringing from the applause of the crowd - but as the music swells, her high heels and hair extensions fade away until she is left alone in a darkened room, silently sobbing.

The scene was unplanned, and the tears were real.

"I was just in this abyss," she says, recalling how the video shoot brought back the feelings of "loneliness and anxiety" she'd poured into the lyrics last year.

The single is the first taste of the star's eagerly-anticipated third album, due early next year. And, just before she played BBC Radio 2's Hyde Park festival, Ballerini talked about the making of the record, being inducted to the Grand Old Opry at the tender age of 25, and the time Beyoncé's sister stole her luggage.

The singer has been part of a new wave of upstart country musicians that also includes Maren Morris and Kane Brown

Let's just take a moment to admire this glitter ball.

I mean, honestly, that's all I really should talk about. It's amazing.

Your last couple of singles have had a poppy, glitter ball feeling, but Homecoming Queen is more heartfelt. What inspired it?

I was touring really heavily and on [social media] I was only really showing the really cool moments of my life - on stage or on a red carpet, all that kind of stuff.

What I wasn't showing was that I was feeling really painfully insecure. So I wrote this song to say it's OK to feel what you feel, and it's also OK to share it, because we're all human. You're allowed to have a bad day, you know?

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The pressure to be "Instagram perfect" can be very damaging.

Yes, I think we've lost connection to other people because we're not sharing those vulnerable moments. So I wanted to be the first one to be like, "Well, here's an ugly cry!"

Which leads straight to the video. How nervous were you to film it?

I collaborated with [director] Shane Drake on the treatment, and we knew it would be emotional - but I wasn't really planning on losing it.

So what happened?

When we'd shot the whole thing, Shane squatted down by my chair and said, "All right, we've got what we need but we're going to do one more take for safety."

Then he said, "Listen, I know you wrote the song. I just want to know why you wrote it," and he got up and walked out.

And I just snapped back into that place of writing it, of feeling lonely and insecure and anxious, and I lost it, and that's the take that you see.

Homecoming Queen is the first taste of the new album. What stage are you at with that?

We have 10 songs done, hundreds written, and we're trying to figure what other colours and textures we need. There's a song with horns, a song with a string quartet, two collaborations that are polar opposites, musically. I'm just having fun.

Lyrically, your last album covered two years, from a horrible break-up to getting married. Is this the next chapter?

It's not. This time, I took the pressure off having a concept and just let myself write. And I wrote like crazy. I wrote more country than I've ever written and more pop than I've ever written. We put the saddest song out first.

You were inducted to the Grand Old Opry earlier this year - at quite an early stage of your career, if I'm right?

I know, I didn't expect it to happen so soon.

How did it come about?

It actually happened on stage. I was playing the Opry the same night as a Little Big Town, and they texted me and said, "Hey, do you want to sing Girl Crush with us?"

But when they brought me out, they sang in four part harmony, "Kelsea, do you want to join the Opry?" and I just sobbed. It's a running theme.

You were inducted by your idol, Carrie Underwood. What was it like to perform with her on that stage?

The coolest part wasn't even anything that people saw. I was rehearsing backstage with Carrie, facing each other with our lyric sheets and working out who's singing what, when all of a sudden we hear a third harmony come in. It turned out Keith Urban had been roaming the halls of the Opry and he just walked in the room, singing.

To me, that was the moment, because it was like, "This is what it means: You're part of this family forever."

You recently wrote on Twitter that you'd decided to "care more about the meal than the bloat". Have you stuck to that?

Yeah. That's why there's a treadmill: Just run it off. It's fine!

Actually, I'm not a treadmill person, I don't know why I said that. I love cycle class, though.

I don't like spin classes because the music puts me off. I prefer to listen to podcasts if I'm at the gym.

Have you listened to Crime Junkie? Oh my gosh, it's so good. I can't watch CSI because I'm such a chicken but Crime Junkie, for some reason, is my obsession. What do you listen to?

Do you know Song Exploder? There's an incredible episode where Solange picks apart the recording of Cranes In The Sky.

Oh, I have a really funny Solange story! She'd been in Tennessee to play the Bonnaroo festival and we were on the same flight to LA, when she accidentally took my bag. We literally had to hunt her down through, like, 70 people before we got it back.

So basically, Solange stole my backpack.

If she'd ended up in your wardrobe, what would she have been wearing?

I was going to LA for one of the collaborations on my album, so I was trying to look cute because I wanted to take photos while we were recording the vocals. But I was also trying to look casual, 'cause I didn't want to look like I was trying too hard. So I had a giant neon sweater and jean shorts and cowgirl boots. Solange would have rocked it.

The singer's third album is set for release in spring 2020