*Note: Following the publication of this cover story interview, Lewis Capaldi announced yesterday that he has cancelled all his gigs – including last night's Dublin show – until Glastonbury (June 24).

If I were an arena-filling pop star, I’d make it a contractual stipulation to have bank holidays off so that I can spend some quality time with my money. Lewis Capaldi, however, is starting his Easter Monday by talking to Hot Press and then racing across town to soundcheck at the MGM Music Hall, the swanky new venue next-door to the Boston Red Sox’s famous Fenway Park baseball stadium.

Like the rest of the Glaswegian’s US tour, it’s a complete sell-out with scalpers asking for – and getting – up to a thousand bucks for a ticket.

Lewis is a third of the way through the 25-date jaunt, which has turned into a bit of a surprise guest-fest.

“The Jonas Brothers came out and did one of their songs, ‘Lovebug’, with me at Radio City Music Hall in New York,” he beams. “They’re very easy-going and chilled. I’d gotten a text from Kevin Jonas asking if I’d go on stage with them in London, but I was in America so they said, ‘We’ll come over to you!’ They’re so pro. They didn’t do the soundcheck but turned up, walked on and, boom, fucking nailed it. I suppose they’ve been doing it for 15 years or more but even so… They’re lovely guys and I always enjoy spending time with them.”

Among the backstage well-wishers in Washington were Wayne Rooney who’s in charge at D.C. United, and his Wagatha Christie wife Coleen.

“Wayne’s cool, I really enjoyed his company,” Lewis enthuses. “It was Coleen’s birthday so they were both in great form. He was telling us a bunch of stories backstage, which were fucking hilarious.”

Such as?

“What happens backstage stays etc. etc.,” he laughs. “He’s just one of those people you immediately warm to. Coleen’s sound too.”

At the height of Oasis’ fame, Liam Gallagher said that he’d swap all of the platinum discs, Knebworth sell-outs and mountains of coke for the opportunity to play for Man City just once. Would Lewis trade it all in similar fashion for his beloved Celtic?

“Not in return for a single game but for a career in football, absolutely,” he nods. “The idea of being an athlete and fucking amazing at football… I’d love to be really good at sports, but I’m fucking shite at it!”

This isn’t entirely true with Lewis stepping up to the oche before Christmas at the World Darts Championship in London where he won a nine-arrows challenge – and then planted a celebratory kiss on Niall Horan’s lips!

“I smashed it and I fucking won!” he beams. “I’ve got a dart board in my house and one of my all-time heroes is Alan Souter who’s from down the road in Arbroath – I’m telling you, he’s the guy!

“Niall – who’s good as well – was meant to do the challenge with me but shat out of it. He’s made up for it, though, by buying me some golf clubs. I was like, ‘Ah, okay, I’ll dip my toe in…’ and now I’m obsessed!

“I don’t know what handicap he plays off, but I can’t imagine it’s very high – Niall is religious about it and also has his Modest! Golf Management company.”

Which currently has fifteen top pros on its books. We’ll come to his own How I’m Feeling Now documentary in due course, but Lewis was the former One Direction-er’s travel buddy last year on the Niall Horan’s Homecoming: The Road To Mullingar Prime Video special.

Niall Horan and Lewis Capaldi

“I can’t believe that was a year ago,” Capaldi resumes. “All we did was drive around and drink pints. Separately obviously – that would have been an interesting documentary! I know everyone says it but I genuinely love Ireland to fucking bits. Nobody was questioning me about my mental health at that point. I’d go back in a heartbeat.

“As part of the documentary, Niall and myself busked on Grafton Street. I hadn’t done a ‘Let’s go and surprise people’ thing before, because I had visions of me standing there with a guitar and no one batting a fucking eyelash. It was like Beatlemania, though, the way Niall drew people in. I still wouldn’t risk it on my own but it was great fun!

“Anyway,” he continues, “he crashed my gig in Atlanta. He ran on and gave me a hug – no kissing this time – and ran off again.”

Lewis was the surprise guest himself in January when he followed in Taylor Swift and Charli XCX’s footsteps by popping up on stage in Newcastle with The 1975.

“I was in the middle of a tour – it was one of my days off – but I thought, ‘I have to go down just for the joy of it’. I got them to put up ‘Introducing special guest, Harry Styles!’ on the big screen. The whole place went fucking mental, losing their shit – and then I walked out. There were loads of horrified Harry fans going, ‘Fuck, he’s let himself go!’

“I actually wrote a song with Matty Healy,” Lewis reveals. “I fucking loved it but it was just a bit too-out-there for this new record. I really want to hang out and work with him again ‘cause he’s a fucking subversive pop genius. He just sees the world from a different angle. Matty gets a lot of criticism for his on-stage antics, but most of the time he’s sending himself up.”

As well as supplying his Netflix documentary with its title, ‘How I’m Feeling’ – sample lyric: “No sense of self, but self-obsessed / I’m always trapped inside my fucking head” – also provides his imminent Broken By Desire To Be Heavenly Sent album with its somewhat unsettling last track.

Described by Lewis as “the most personal song I’ve ever written”, it doubtless contributed to the Sunday Times’ recent ‘Pop Star On The Edge Of A Breakdown’ headline with “There’s a very real possibility that I’ll have to pack music in” as the pull-quote. All a bit (well, a lot) reductionist but, hey, Rupert has to sell papers!

“I wrote it in Cumbernauld in Scotland, which is probably why it’s so doom and gloom: it’s always grey there!” Lewis deadpans. “I did it in this great wee studio with Tobias Jesso Jr. who’s from Los Angeles and used to recording in really glamorous locations with people like Adele. I think he did the new Niall Horan one in the Maldives, so imagine the culture shock he experienced coming to Dunbartonshire!

“It’s the last song we wrote for the album and my favourite because it’s so different to anything else I’ve put out in terms of lyrical content. There’s happy bits and songs about break-ups and then ‘How I’m Feeling’ arrives with black clouds overhead. It doesn’t feel like a nice tying a bow around the album – it’s more, ‘Oh, fucking hell…’ which is what I wanted.”

Another gazillion-seller in the offing is ‘Any Kind Of Life’, a turbo-charged ballad, which emotionally cuts to the bone and is possibly his finest 3mins 19secs yet in the vocal booth.

“Thank you, man, cheers,” Lewis says, visibly blushing. “That was quite one take-y, because I don’t think I had enough breath in my body to do it again. I’m usually granular in that if I don’t like the way I’ve said a word or whatever, I’ll just keep going at it. You can drive yourself mad sometimes. The ‘Any Kind Of Life’ vocal take was done the day we wrote it, though. There was no overthinking – it just came out so, yeah, there was nothing blocking the emotion. It’s going to be an interesting one to sing live, that’s for sure!”

Tugging ever harder at the heartstrings is ‘Pointless’ – sample lyric: “I bring her coffee in the morning / She brings me inner-peace” – which if slow-sets still existed would be the song the DJ sandwiches in between ‘Bridge Over Troubled Water’ and ‘The Wind Beneath My Wings’.

Does Lewis consider himself a romantic?

“In a sprinkling rose petals on the bed sort of a way, no,” he cackles. “I tend to be over-analytical and think, ‘Oh, that’s a bit cringe and soppy’ listening back to something like ‘Pointless’. I’m not one for grand gestures, but to write a love song that resonates, you have to be a little bit of a Lothario.”

I’m thinking how adroitly Lewis has managed to avoid Difficult Second Album Syndrome when he quickly adds, “I’m fucking stressing here thinking back over it. After the success of the first one (Divinely Uninspired To A Hellish Extent), I should have been like, ‘I’ve got this fucking tied up and in the bag: I know how to write a hit song blah blah blah’ but, nope, I just felt more and more confused. ‘What the fuck is a big song?!’ I didn’t know anymore.

“At no point making Broken… did I think, ‘I can relax now.’ I still don’t feel relaxed about it. I’m an anxious person by nature, so I suppose I’m just predisposed towards that.”

Gary Lightbody told me has no problem writing and recording intimate love/lust/break-up songs, but panics the night before they’re released, in case the person they’re about gets the hump with him kissing and sort of telling. Will Lewis be similarly worried on the evening of Thursday, May 18?

“If I’d written something like Lily Allen’s ‘Fuck You’ – ‘I think you’re evil’ – I would be, but it’s mostly nice stuff I’m saying,” he notes. “There are only one or two people the songs could be about. If they want to get in touch and ask me questions, I’m more than happy to fill in any blanks, but hopefully I should be okay in that regard.”

There’s a scene halfway through the How I’m Feeling Now doc where his manager, Ryan Walter, and musical director, Aidan Halliday, rubbish the new songs Lewis has just played them. To me it seems a bit cruel, but Capaldi is grateful for their extreme candour.

“My manager is a great and brilliant guy,” he insists. “He’s single-handedly responsible for the success of my first album. Ryan’s quite driven but I’m a lazy cunt. As observant as he’s been of my mental health, if a song’s shit, he’ll tell me it’s shit. If I send him songs that he doesn’t like – and I’m shitting out four or five a week at the moment – he just won’t reply, which is great, done! It doesn’t matter what he thinks, though, if it’s something I have a massively strong feeling about. He didn’t like ‘To Have A Feeling’, which is my favourite song on the album, but there it is at the end bringing the mood down!”

His support network doesn’t end there, with Lewis reading out an email from Elton John in How I’m Feeling Now that says, “Dear Lewis, I was talking to Ed (Sheeran) yesterday and we talked about you. He said you were feeling a bit like an imposter. Bollocks! You are totally your own man. Your album is still riding high all over the world and it’s also your first album. You are also great live and a wonderful singer. You are also very funny and original, I mean this sincerely.

“Stop it now please,” the Dwight boy concludes, “or I will come up to Suffolk and bring out the latent homo in you. Buckets of love, Elton.”

Which, I think you’ll agree, is quite the electronic correspondence to be receiving.

Elton John

“He just cares about the wellbeing of artists,” Lewis reflects. “Obviously he’s been through the ringer himself and understands the affect it can have on you. Elton invited me to go for fucking lunch at his house and, like the other times I’ve met him, the conversation from his side was mainly about my well-being.

“My record company, as well, refused to put the first single out from this album until I showed them I was mentally looking after myself.”

Capaldi constantly berates himself for oversharing but his honesty today – and in the How I’m Feeling Now documentary, which delves deep into his mental health travails – is refreshing and all too rare in an industry that media trains its young.

“The concept was, ‘Me on stage partying in front of thousands of people and generally having a fucking amazing time’, but that’s not how it turned out,” Lewis resumes. “If I’d known that it was going to be an exposé of my mental health, I probably wouldn’t have done it – it’s not your typical ‘promo for the new album’ – but I’m so happy we did because it’s been very cathartic. I feel weirdly at sort of peace with it all.

“I was nervous because it really goes into depth about my anxieties and stresses and Tourette’s – you’re put on display for everybody to see – and scared in case people thought, ‘Here he is in a very privileged position whining…’ I know there are people in the world going through much worse shit than I am. That’s what worried me but I feel chill about it now. The responses I’ve been seeing have been pretty incredible. I’ve had more messages about the documentary than I have about my music which, if I’m being honest, is quite annoying!”

Shortly after our chat in Boston, Lewis’ sister, Danielle, hit back at trolls who accused their parents, Mark and Carole, of being “harsh and cruel” towards him in the documentary. She shouldn’t have had to because all they come across as is loving.

“No, thank you, I agree, man,” Lewis nods. “There’s a scene where I’m talking to my parents about my twitch and my anxiety. Some people have seen that and taken it the wrong way. ‘Oh, his dad’s putting pressure on him.’ People sometimes don’t get the bluntness of a Scottish parent. I wouldn’t have got to the point where I am now without their support.”

A somewhat embarrassed Bobbie Gillespie from Primal Scream told Hot Press that whenever he’s interviewed by MTV in the States they stick subtitles on him.

“Me too, exactly the same,” Lewis rues. “The default position on How I’m Feeling Now on Netflix is subtitles. What’s been bizarre the past couple of days is the number of Uber drivers in Boston asking me, ‘What part of Ireland are you from?’ They’re all proud Irish-Americans but can’t distinguish between the Irish and the Scottish, which is hilarious but there you go!”

I remember Niall Horan telling me that the most important thing he’s learned as an artist is how to say “No!” and stick to it. Has Capaldi reached that point yet?

“Not quite – but I’m working on it!” he grins. “Niall’s fucking great to bounce stuff off of. It’s mad to think that he’s almost fifteen years into the game at this point – especially given how young he still is. When I ask him questions, he answers them like a friend rather than a big brother imparting some great wisdom on me. I think that’s a really important dynamic.”

When I asked Niall about moving over to London, he worryingly started off by telling me that one of the first things he did was check out where all the girls’ schools were before adding the all-important “so I can make sure that I’m not walking past them at going home time and get mobbed.”

Are there things that Lewis can’t do now because of his celebrity?

“That’s funny about Niall,” he laughs. “I can’t take a handful of ecstasy and parade around the street – not that I was doing that before. I can’t be inebriated to the point where I don’t know where I am or who I’m talking to, but I’m not Justin Bieber or a former member of One Direction. I can kind of float around and be myself. I don’t know if it’s because I’ve been quite open and honest about everything, but people don’t think of me as being famous. When they come and ask me for a picture, it’s friendly as opposed to frenzied.”

Credit: Alexandra Gavillet

Did the fact he’d been writing and performing songs from the age of eight – apparently there are tapes and videos to prove it – make Lewis a teenage hit with the girls?

“I was hoping it would but it never fucking happened,” he rues. “Let’s be honest, I wasn’t the best looking kid. I had baggy ears which I hadn’t quite grown into yet and, because I didn’t really enjoy sports, was chubby. I was like, ‘I need something to help me out here. Yeah, fuck, I’ll play guitar and sing and da da da and it’ll be great!’ You watch all these documentaries on TV and think, ‘They’ve got all the girls’. They might of but I didn’t. Seriously, if there’s anyone out there that’s thinking, ‘I’m going to become a singer-songwriter for the romance and the ladies or the guys’, I’d say, ‘Don’t bother.’ For me it was not a fruitful endeavour!”

Lunch at Elton’s aside, what’s the most star-struck Capaldi has been?

“Meeting (legendary Celtic striker) Henrik Larsson in Copenhagen Airport,” he shoots back. “He was playing golf somewhere I think and didn’t seem enthused by us asking him for a selfie. I imagine that wherever he is in the world, there’s a group of drunk Scottish guys going, ‘Henrik, can we get a picture with you?’ but he was gracious enough to oblige.

“Second to that would be going to see Paul McCartney talking about a book in the South Bank Centre in London. I was sitting in the front-row and audibly gasped when he walked on. He’s one of those people where you’re like. ‘Wow, that’s fucking Paul McCartney!’ That’s as big as you get. You’re a piece of living history.”

I almost fainted when he gave me one of his famous Macca double thumbs-ups.

“Well, you would, wouldn’t you?” he sympathises.

Lewis will get to skull pints of Guinness – and possibly hang out with Niall Horan – again in September when he headlines the Saturday night at Electric Picnic.

“Whether it’s the Olympia, Malahide Castle or that place down by the river, the 3Arena, we always have a fucking amazing time when we play in Ireland,” he concludes. “To now be headlining such a massive festival there is off the scale surreal – I mean, how the hell did that happen?”

Broken By Desire To Be Heavenly Sent is out now. Lewis plays Electric Picnic on September 2 and Belfast Vital on September 3.