Niall Horan on Elton's advice and touring with no trousers

In a world filled with tortured musicians making music about anxiety and depression, Niall Horan is an outsider.

Affable and charming, he arrives for our interview whistling The Beatles' Get Back, wearing a sweater as comfortable as his demeanour.

Plonking himself down on a hotel bed with a breezy, "how's it going?", the Irish singer reclines into a conversation about his new album.

Titled Heartbreak Weather, it was inspired by his break-up from a girlfriend, thought to be actress Hailee Steinfeld - but the star was determined not to make it a downer.

"I was just like, 'Come on, have a laugh, you can't go around moping," says the 26-year-old. "And it turned out to be the most fun I've ever had in the studio. A really fun year.

"And," he adds, "I'm gonna have so much fun doing the shows."

Optimism seems hard-baked into his outlook - but it could easily have gone the other way.

At the age of 16, Horan auditioned for X Factor, where he was absorbed into the boyband One Direction, becoming a household name almost overnight.

Between 2010 and 2016, they sold 50 million records and toured the world, pursued by devoted fans - some of whom would hack into hotel security cameras and write sexualised fiction about Horan and his bandmates.

Horan said his "childhood was cut short" by the experience, and there were times the lack of freedom became oppressive.

In 2016, the singer chastised a fan who'd taken a picture of him sleeping on a transatlantic flight. Last year, he told the Telegraph he developed "a fear of going out cos you'd get stopped every five seconds".

Things changed when the band went on hiatus. Horan took an extended break, "mooching around" on a back-packing tour of Asia ("a monkey stole my wallet," he recalls). By the time he returned, he was able to walk down the street unmolested.

But he refuses to holds a grudge against the fans that were his constant shadow for six years. In fact, he recognises the impulse to get close to your idols.

"It was like a circus," he recently said of his stint in 1D, but "I understand why people hang out outside of hotels".

These days, Horan has not just met his own musical heroes but he keeps them on speed-dial.

"Elton John's really supportive of my songwriting," he says. "He's great [for] constructive criticism or just straight up criticism. You get actual feedback.

"And Don Henley [of The Eagles], I send him bits and pieces and he'll absolutely, no problem, tell me if there's something wrong with them.

"But that's what you need. I mean, there's a reason I'm asking for help - because I'm expecting a bad answer. And if Don Henley has an idea to make the song better I'm like, 'Well, you wrote Hotel California so I believe you.'"

The sounds of his 70s soft-rock mentors reverberate through Horan's new album, most notably on the piano ballad Put A Little Love On Me.

Racier tracks like Small Talk and Nice To Meet Ya find the star showcasing a gruff and hitherto-unexplored baritone that, he admits, was borrowed from Elvis.

"Those songs came from a jam and that, in turn, invites sexier lyrics, for you to be a bit more vulgar," he says. "So I was getting into character and having fun and it ended up sounding like Elvis.

"But I'm not sure I'll be breaking out the rhinestone catsuit just yet."

The album is distinctly more uptempo than his folksy debut, Flicker (a US number one); a decision that was informed by two years on tour.

"I had a great time playing shows but the songs were quite chilled," he says.

"I was looking at faces in the crowd and you can see when people want to be sad - but then they also want to be jumping up and down, wrecking the place.

"I needed a bit more like jumping up and down and stuff."

He started writing the songs at his home in LA towards the end of 2018 - not because he had a burning desire to get back in the studio, but because he was cooped up at home after having surgery for a sinus problem.

"I just started messing around, you know?

"I'd be watching something on TV and I'd be singing something or I'd pick up a guitar and have a little tinker around and before I knew, I was writing full songs.

"I was like, 'Jesus, I didn't plan on this but it's happening.'"

The initial batch of songs were inspired by his break-up (he doesn't mention Steinfeld by name, and their relationship was never confirmed - but we're also instructed not to ask about her during the interview, so draw your own conclusions) but as the year progressed, the album took on a broader concept.

The idea was to "correlate my feelings with different weather patterns," he explains, with the album reflecting "all the different angles of a break-up".

Everywhere captures that feeling of "seeing your ex everywhere you go", while Arms Of A Stranger is about the inevitable rebound relationship.

Nice To Meet Ya describes "the egotistical part of the break-up where you want to go out and flirt and have a bit of a good time," but the album ends with a twist: "I'm still in love with you".

"So you start off with start a relationship, you wind your way through all these songs and that's the last thing you say," he says with a twinkle in his eye.

While promoting the album, Horan has deliberately cut loose from the po-faced "serious musician" image he projected on his first solo outing.

He announced the tracklisting via a fake weather forecast, dressed up as one half of The Proclaimers on James Corden's US chat show, and came up with the goofy storyline for his latest video, No Judgement.

The clip, directed by Drew Kirsch, features an elderly couple for whom personal boundaries are no longer an issue - whether that means eating mayonnaise by the spoonful in bed; or using the toilet while their partner is in the bath.

"I heard my granny talking about it: You get to a point in your relationship where nothing matters," explains Horan. "Old people don't judge each other at all because they've lived enough life to not care."

As if to prove it, he says that Barbara, the LA native who plays one-half of the video couple, didn't just embrace the scenarios he'd scripted, but suggested some of her own.

"She was like, 'By the way I can do a plank if you want,'" he laughs. "And she started planking in the middle of the garden.

"She was up for everything. She was having a great time."

Another person who seems to lack proper boundaries is Horan's long-time friend Lewis Capaldi - with whom he's touring the US next month.

After the shows were announced, Capaldi claimed the duo would take to the stage "bottomless," branding it "the no-pants tour".

"Is that what he said?" Horan exclaims. "I don't know what's wrong with him. I'll probably be wearing clothes."

But while the friends have been plotting a joint tour for a long time, Horan says they'll be forgoing a party lifestyle on the road.

"I'm big on value for money - and there's nothing worse than going to a gig and looking at someone that's tired or bored," he says.

"I have to perform for like an hour and 40 minutes, so I can't [go partying] every night. I'll be in the gym every day and Lewis said he's doing the same, so it's gonna be the chilled out version of us."

And if he takes care of himself, can he imagine playing stadiums in his 70s, like his mentors Elton John and Don Henley?

"I'd absolutely love to be there if the people will have me around," he says.

"That's what you want. You strive for legendary status and if you get it, you get it, and if you don't, well at least you tried."

Niall Horan's album, Heartbreak Weather, is out now.

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