"I wouldn't say it's double billing: I think I'm the supporting act," demurred the designing daughter, who strung balloons spelling out "Stella [Hearts] L'Pool" over the stage at the Liverpool Institute for Performing Arts, the site of her afternoon fashion event and, formerly, boys' school of her father and his brother, Michael.
"It's so funny seeing Stella here in this building where we spent seven or eight years looking at that," uncle "Mike" said as he snapped photos of his niece against a backdrop of classroom windows smudged with rain.
Despite the dreary weather, McCartney's show was a high-octane affair, with the stage rocked by boy band Palladium, romanced by velvet-voiced singer Candie Payne and then ripped up by frenetic Cornwall dance troupe Flava.
Those performances flanked a showing of McCartney's fall-winter 2008 designs before a crowd that included Sir Paul, Yoko Ono, Olivia Harrison, George Martin and Coleen McLoughlin, bride-to-be of soccer deity Wayne Rooney.
Some 400 Stella fans, including some from as far away as Japan, turned out for the benefit fashion show, timed to coincide with Paul McCartney's concert to mark Liverpool's status as this year's European Capital of Culture.
"I think it's beautiful they're finally coming together," said Ono. "That is family power."
Backstage, as his daughter put the final touches on her looks, Sir Paul confessed to sometime pangs of nervousness on her behalf. But not many.
"She's the biz," he declared, gathering her up in a hug.
McLoughlin was mum on details about her wedding dress — she has an exclusive with OK magazine — but revealed plans to launch a makeup range and style guide this fall. And what exactly do Liverpudlians like to wear? "They like to be glamorous: make the most of themselves," she explained.
For her part, McCartney cheered the fact that girls from northern England aren't shy about showing off their legs and shoulders — and seemingly impervious to evening chill. "It would be great if everyone were like that. There'd be no need for fur coats," she mused.