Who’s that girl?

“I can’t say anything,” he says. “I’m sworn to secrecy.” Make of that what we will.

Macdonald, 38, is rapidly gaining quite a reputation for being an outspoken fashionista, thanks to his role as a judge on TV series Britain’s Next Top Model, sitting alongside Elle Macpherson.

“At the end of the day, I’ve been in the fashion industry for 15 years and I come from a very working class background and I’m just like everyone else – there’s nothing special or different about me,” he says, in his lilting Welsh accent. Originally from Merthyr Tydfil, he studied at Brighton and the Royal College of Art, then designed at Chanel and Givenchy, before launching his own label in 2004.

“If I was watching, I would expect someone to be honest. I’m giving my personal opinion.”

Last year there were reports that he had criticised Cheryl Cole’s style in public at a party (the word “chav” was said to have been mentioned), but Macdonald is happy to set the record straight.

“That stuff about Cheryl was load of lies,” he says. “Me and Cheryl are really good friends. She gets a lot of stick for all sorts of reasons. She’s been a personal friend for about eight years. I have dressed Girls Aloud personally. It’s been a brilliant experience seeing how she is growing and becoming a superstar.” And note, it was Julien Macdonald who designed Cole’s daring slashed suit for her single Fight for this Love. A fashion coup indeed.

Cheryl would look fabulous wearing his new line for Debenhams, Diamond by Julien Macdonald, launched earlier this month. “So far it’s blown us away. The sales have been incredible. It’s all really exciting,” he says. “It’s always difficult when you launch a new line.”

The target age range is 19-25, perhaps the younger sisters or even daughters of the clients who choose his more established Star womenswear range.

“It’s for young girls who adore fashion and going out. I have a quote: ‘For a Diamond girl, it’s Saturday night, every night’.”

The face is 17-year-old Tali Lennox, daughter of legendary singer Annie. “She’s a really stylish girl and when I asked her if she’d like to, she said ‘I’d love to’,” Macdonald says.

The most important factor for designing a High Street collection is affordability, he says. “You can have the most amazing range, but if you can’t hit that price range, it’s never going to be successful.”

Diamond by Juilen Macdonald is available at Debenhams White Rose and Briggate in Leeds, Meadowhall Sheffield and Doncaster.