Archive purposes only:

When the director Jamie Lloyd offered Nicole Scherzinger the lead in his new musical production of Sunset Boulevard, “I was like, ‘Are you out of your mind?’ First of all, I still look great under bright lights. And isn’t that an older woman who is, like, an old relic? How does that even remotely have anything to do with me?”

The former Pussycat Dolls pop star couldn’t see herself as Norma Desmond, the tragically faded and forgotten, psychotically deluded former silent movie starlet who at 50 still dreams of a comeback. Hand on hip, adopting a deep southern drawl of indignation: “I was, like, ‘Yo, this chick is crazy. I don’t want to play her. She crazy.’”

Scherzinger, 45, had planned on being in Hollywood, filming the next series of the glossy reality show The Masked Singer. Instead she is in leggings and trainers, eating sweaty salad out of a plastic box, sitting in what looks like a broom cupboard, on her lunch break in an east London rehearsal studio.

What persuaded her? “When I listened to the music I felt those were songs I could have written, like they were my songs. This is a completely different show than the musical people know. I feel like we might as well change the name of the show because it’s a completely different story we’re telling.” In her performance Desmond “is not crazy. She’s madly passionate about what she feels like she was put on this earth to do. She’s in love with her art. And there’s nothing tragic or pitiful about that.” She fixes me with a heartfelt stare. “She’s wanting to be seen for who she really is.” And so too, in Sunset Boulevard, is Scherzinger.

“People are going to see a very different side to me, aren’t they? Like they’ve never seen before in 45 years. I would like people to know me for the artist side of me.”

The Hawaiian-born singer began her career at 14 in youth theatre, but became world famous in 2005 for singing the immortal line “Don’cha wish your girlfriend was hot like me”, in the Pussycat Dolls’ debut hit single, while wearing thigh-high leather boots and a bra. The deeply religious granddaughter of a Catholic bishop, brought up in Bible-belt Kentucky, was never comfortable with the band’s sexpot image. But she worked hard, they sold 55 million records, and after they split in 2010 she joined the UK X Factor’s judging panel, dazzling ten million viewers each week with high-octane glamour, occasionally twerking on the judges’ desk.

Dubbed the hardest-working woman in showbiz, she has built a portfolio career as a multidimensional celebrity, making two solo albums and appearing in the hit musicals Cats and Rent, multiple TV reality and panel shows, three movies, Müller yoghurt commercials and the King’s coronation concert. Even off duty she’s seldom out of the tabloids; from 2007-15 she was on the arm of the F1 driver Lewis Hamilton and since 2019 with Thom Evans, the former Scottish rugby star to whom, as of June, she is engaged.

Scherzinger so rarely gives press interviews that I’d arrived expecting a highly controlled, maddeningly unrevealing conversation, not this earnestly unvarnished candour. “I’m very grateful for the jobs that I’ve had,” she is careful to say, “and for the people I’ve gotten to connect with me on different stages, like The X Factor. But am I proud that people know me more for that than for my natural talent? It’s something I have to re-evaluate in my life.”

Her expression is deadly serious. “Musical theatre was always my first love. And deep down inside I know that I am chosen. I know that I have something that no one else has in this world. You give me a song, and you put me on that stage, and it’s just a gift that I have, the gift to make people feel something. It’s my innate gift from God.”

Having grown up “dirt poor”— her mother was a clerk, her stepfather a welder — she works hard to support them and her grandparents back in the US. “Coming from nothing, my family needs me. My money is their money.” The decision to forfeit her highly paid job on The Masked Singer to be in Sunset Boulevard was, therefore, difficult.

“But I had to follow my heart. I chose this because this is where I belong. You don’t do this for money or cameras. You do this for love, the love of art — literally for art’s sake. And how are people going to know the artist side of me if I don’t put it out there? So it’s up to me to start making those choices in my life, to put myself where I can really share my true talents.”

Scherzinger’s legendary work ethic is in overdrive. She gets up 6.30am, takes a sauna “to sweat out toxins”, and works out with her trainer before rehearsing from 10am, six days a week. The cast tease her for always working through lunch break. At 6pm she goes straight home to an evening shift on the phone to her team in Los Angeles, and makes notes before getting to bed “at 12, if I’m doing good. If I’m not, more like 4.” She has to take something to help her wired brain sleep. “CBD gummies are legal in LA,” she says, grinning. “They work for me.”

Her therapist used to tell her “I lash myself forward”, and wasn’t wrong. “My mentality is: if you’re not suffering enough, then it’s not going to be good enough. Criticism is good for me, it ignites something in me.” She has been very struck by other cast members’ easy familiarity with compliments. “I’ve noticed a lot of people here, they get a lot of praise. I didn’t grow up like that at all.”

She has “had enough counselling” by now to know that a little less work would “be healthier, but I’m still finding that balance”. Self-discipline gives her “the security and the confidence I need because I am very insecure”, she says. Does self-doubt set in when she relaxes? “To be honest with you, I’ve never not been disciplined, so I don’t know.”

Her drive to do justice to the role of Desmond is turbocharged by her empathy with her character’s experience of ageism in Hollywood. “It’s just as relevant today. And it’s still very brutal.” My assumption that she would be too young to have any experience of it makes her laugh. “Even if I look like I’m 37 or something, the moment somebody knows your age they will just —” and she draws a hand across her throat. “So it’s relevant to parallels in my life.”

She can empathise, too, with Desmond’s fear of no longer meeting Hollywood’s impossible demands of female beauty. When she was in the Pussycat Dolls, Scherzinger used to spend more than five hours a day in the gym, and suffered for years with bulimia. Their manager told her to lose weight when the band was formed. “But I didn’t need anyone to tell me. I’m my hardest critic of myself, so I was the worst voice, right?”

Nowadays she can happily let her body “hibernate” when not working, and “fluctuate by 10 to 15lb, and that’s fine”. She celebrates the body-positivity movement pioneered by plus-size stars like Lizzo “absolutely, a million per cent. Having had body issues my whole life, to go down Oxford Street and see big women models in these huge stores, it’s so nice to see women of all sizes normalised. We didn’t have that growing up.”

Scherzinger’s casual profanity makes her sound more British than American. “I’m an adopted Brit. My friends in America know me as a Londoner, and I’m proud to be. I’m with this country, I’m proud of it.” Married life with Evans will have a base in Britain. “But we travel a lot, and I like that.”

The wedding will be in Hawaii, conducted by her grandfather, followed by a reception “somewhere in Europe”. Beyond that “I haven’t even thought about anything. Everybody’s, like, what’s the plan? I’m like, yo, I gotta find Norma Desmond. Until I find her, and I open this show, and I am proud of it, I’m not thinking of anything else.”

I ask if she has thought about The X Factor, which is reported to be returning to our screens next year. “It is? I had no idea.” Would she consider rejoining the judges’ team? Her reply makes me think that the buzz about Sunset might just be starting to quiet her punishing inner voice. “Yeah, I would,” she says with no discernible enthusiasm. “If,” and her eyes start to gleam again, “I’m not swept away on the stage, changing people’s lives.”

Sunset Boulevard is at the Savoy Theatre, London WC2, until January 6