Everyone loves Kylie. When Gary Barlow, on host duty with the Queen at her Diamond Jubilee concert, needed a lovely assistant, he chose Kylie Minogue, OBE. After a performance as a punk pearly queen, the dainty princess of pop changed into angelic white to guide the Prince of Wales perfectly through the rock-royalty introductions. Minogue's hotpants may be naughty; she isn't.
After celebrating her own silver jubilee in music – she released her first single, "The Loco-motion" in 1987 – Minogue could be forgiven for a little anti-establishment rebellion. No one, however, would have expected it to take the shape of a Leos Carax film, Holy Motors, which premiered at this year's Cannes Film Festival.
Carax, 51, is an experimental French director; his last film, about incest, Pola X, was released in 1999. Holy Motors, in which Minogue has a supporting role, has been described by critics as "a lunatic odyssey" or, more succinctly, as "bonkers." And Minogue loved every mad minute of it.
"I'm sure I'm going to wake up and find out it's been a dream," she confesses. "It's been the most incredible experience – making the film, meeting Leos. It's mind-blowing. I've experienced quite a lot in my life but this is something else. And even though I just came off the biggest tour of my life, I'd put this part as a highlight of my career."
Fresh-faced, eager, joyful, she looks years younger than her 44 years and that's nothing to do with the cosmetic fillers it's widely believed she uses. She declares herself "gobsmacked" by the positive reaction to Holy Motors.
The film may be mad, but it's not bad. Les Amants du Pont-Neuf actor Denis Lavant stars as Monsieur Oscar, the "employee" of a "firm" who journeys from one life to another, from beggar to businessman. Minogue is another "employee". She gets to keep the day job too, at one point breaking into a tune written by Carax and Neil Hannon of The Divine Comedy.
The movie received a long ovation from the notoriously tough Cannes crowd. She may be terming it a debut, but as movie experiences go, she went straight to the top.
"I had no idea that it would ever show at Cannes, though," she says, " It was a really leftfield decision for me to take the part. I knew that Leos was adored in France, that there was excitement he was making a film again, but he was not on my radar at all."
Leftfield isn't such an odd direction for her to take. Back in the early 1990s, she was the prize racer of the Stock, Aitken and Waterman stable with 13 Top Ten singles in the UK – and then she bolted. She took up with Michael Hutchence, and then later produced her indie album, Impossible Princess. One of the tracks she did at that time – a duet with Nick Cave and the Bad Seeds, "Where the Wild Roses Grow" – won her the part in Holy Motors.
"Leos didn't have any idea who I was, he had heard nothing I'd done except that duet with Nick. I found that all very refreshing. I was suggested to him by our mutual friend, [White Material director] Claire Denis and we met in Paris. I said to him, 'you're either very brave or very crazy to give me this role'. And just like that – he hired me."
Her roots are in drama, of course – in the Australian soap Neighbours as toothy mechanic Charlenewhose affair with Scott, played by Jason Donovan, preoccupied the nation. Their 1987 wedding attracted 20 million UK viewers. Before that, she and sister Dannii and brother Brendan grew up in the Melbourne suburbs and both sisters worked on TV shows; Kylie started off in The Sullivans, aged nine. She may have done little acting since launching her pop career – a part in 1989's The Delinquents, the fairy in Moulin Rouge and a Dr Who Christmas special – but surely, as Kylie Minogue, if she'd wanted to act, she could have done nearly anything she wanted?
"But this is a film which is an opportunity to do something that is utterly different from what I normally do," she points out. "I wanted the chance to change the way I present myself. I was able to strip everything away and become someone else. That's liberating." Liberating in the sense that she could escape Kylie Minogue, a pop star with a reputation for being perfect?
"Yes. I entered Leos' world, on his terms. And I would turn up by myself every day, without any kind of entourage. That was difficult for my team as I know they would have loved to have been there for the experience and I had to say to them, 'no, sorry – no one is allowed to come'.
"I wanted it to feel like back when I was a kid, when I was just starting out, when I wasn't 'Kylie', with all the machinery and production and hoo-ha surrounding me. I was just a person acting."
She sounds wistful. After a quarter of a century in the music business, challenges must be few and far between. In 2000, she donned the gold hotpants for "Spinning Around" and reinvented herself as such a successful disco diva that one track, "Can't Get You Out of My Head", went to No 1 in 40 countries. She has sold nearly 70 million records and has been awarded an OBE for services to music. Yet it's 15 minutes of acting which seems to have reignited her.
"I was as nervous as hell," she admits. "I had to hand myself over completely to someone else, I had to trust and make myself vulnerable. I do feel that the whole experience has been cathartic. I feel like I have been slightly regenerated, that a side of me has been renewed. It's been a whole different experience from albums and concerts and it nurtures another side of me which has been neglected for a long time."
She adds. "I am just a chameleon, a chameleon who likes to take on different forms. I love being on set, it takes me back to being 10 or 11 years old again. Ideally, I'd like to do a musical in the future, something that would tick all the boxes for me. But to act more – now that would be a beautiful thing."
'Holy Motors' is released later this year