Katy Perry: I'm just a normal girl – a Plain Jane

Katy Perry's private jet stops in Cancun, Mexico, for a couple of hours. This gives the woman equalling Michael Jackson for the most No 1 singles off one album enough time to talk about The Smurfs 2. That's Katy Perry's acting project. Yesterday she worked on her third album in Los Angeles. Tomorrow she will launch her fragrance in New York. Next week it's a photo shoot for Vogue back on her home turf of California.

Up close, she's like something you'd purchase from Ye Olde Fashioned Sweet Shoppe. She is indeed good enough to eat, with a peppermint striped dress; sugared nail polish; black hair like liquorice. She may have been, briefly, Russell Brand's Teenage Dream, but the secret to her success is that Perry is a girl's girl, swapping notes on dresses and nails before the talking officially starts.

It's the appeal of Kathryn Elizabeth Hudson, her real name, to other females that meant she was ideal to reproduce the squeaky goodness of Smurfette, The Smurfs' only girl in the village. Although the movie also stars Neil Patrick Harris and Hank Azaria, in this one, Smurfette has a leading role. Producers claim that 28-year-old Perry was picked anonymously, from a bundle of voices.

“I think that I have this raspy, male quality in my voice that you need for someone like Smurfette,” claims Perry. She speaks in high, clear tones and looks as demure as Scarlett O'Hara, so this seems unlikely. But she insists.

“Oh no, really – I do. And it probably helped at the time that my hair was actually blue,” she adds, with a rueful nod towards her “California Gurls” video. To give her credit, underneath her frock and her lush hair-extensions, lurks an innate sense of comic timing, visible in her music videos and a Saturday Night Live appearance. The Smurfs producer Jordan Kerner says she could go down an acting route if she wanted to.

“That's kind. The comic actresses I admire are women like Amy Poehler, Tina Fey and Rebel Wilson – girls that aren't afraid to be self-deprecating, and they're OK with looking at themselves in bad lighting, women who are more interested in the joke rather than in their presentation.” This is at odds with her cartoonishly perfect appearance, but Perry's big blue eyes are insistent.

“No, I like the idea in acting to play the opposite of how I present myself, as some kind of unrecognisable character. As I've said before, I'm just a normal girl – just a Plain Jane who watered a seed and watched it grow. If I can do it, anyone can. Girls don't need to be physically perfect to succeed.”

Unlike her equally famous BFF Rihanna, Katy Perry enjoys hammering home a positive message to her young fans. She financed her own documentary, Katy Perry: A Part of Me, which started out as a warts-and-all view of her world tour, and which ended up also documenting her break-up with husband Russell Brand. Perry not only exposed herself minus her warpaint, but also bared herself to utter the warning every eight-year-old needs to hear – “love isn't like in the movies”.

Her “moral side”, she says, comes from her strict upbringing in Santa Barbara, California, at the hands of her evangelical-pastor parents, Keith and Mary Hudson, “but I think everyone knows that I am more open. But I hope I make all my decisions with integrity. My grandmother is in charge of my morals,” she adds with a laugh. “I do anything wrong, she'll come after me.

“Of course people have to choose between good and evil,” Perry continues, “but I think no matter what situation we find ourselves in, or where we come from, we can always choose to grow from it. Scars are a reminder of what we have learned.”

Most of Perry's recent growing pains come from her divorce from Russell Brand, whom her mother was reported to have likened to the devil.

Perry recently revealed the last time she'd heard from her Mephistophelian lothario was on New Year's Eve 2011, when he texted her to say he was divorcing her. She then fell for someone second only to Brand in his reputation as a heartbreaker, singer Jon Mayer. She also has since told Vogue she still loved Mayer, but was single. Well known for writing her own material, what will her third studio album, the follow-up to the six-million-selling Teenage Dream sound like? Adele's 21?

“You know, not everything in life is terrible, although I am not singing about how fabulous everything is all the time. I have a lot of fun in my life, and I want my records to reflect that.” How hard was it for a girl brought up with hardly any “secular” music allowed? After moving to Los Angeles, alone, at 17, having recorded a gospel album, Perry went through six years of almost-misses, near-releases and label-dumpings, before breaking through in 2008 with One of the Boys.

“Music is so much who I am. It defines me. I have it inside me and I'll never lose it.” This is why she won't be making acting a priority. “It's definitely a lot of an effort to be an actor, and it's not something just anyone can roll into. I think you get a lot of people thinking, 'if I can act, I can sing, if I can sing, I can act', and it's just not true. I think seriously I would have to train hard for it if I was going to take a job that works 16 hours a day, five days a week, and you have to love it.” This seems remarkably humble, but Perry disputes this.

“I have a lot of friends who are actors and I see how hard they work. I think that it's actually harder and it takes more time than a music career. You wake up at four or five am. That's commitment.

“If the movie would start filming at 11am then I would do it,” she adds mischievously.

Who's she kidding? Katy Perry didn't get here by being a sloth.

'The Smurfs 2' is out on 31 July

*This article appears in tomorrow's print edition of Radar magazine