What was premier milliner Philip Treacy thinking when he designed that love-it-or-hate-it hat Sarah Jessica Parker wore to Monday night’s world premiere of Sex and the City: The Movie? “Well, his mother kept chickens and geese, so he loves feathers and manipulating feathers,” Treacy’s spokeswoman Nina Farnell-Watson explains to PEOPLE. Treacy was approached last week about making the hat — not, says Farnell-Watson, by film stylist Patricia Field but “by someone else.” He received photos of her Alexander McQueen dress and then met with the actress at her London hotel Sunday for about an hour. She tried on some different hat shapes and “found the one she loved,” says Farnell-Watson. Treacy then worked for two days straight and “very late into the night” trimming it with peacock feathers he got from McQueen. (They’re the same plumage used to trim her dress.) Parker — who had no idea what Treacy was planning — first saw the finished hat about two hours before the premiere. “Quite brave of her,” notes Farnell-Watson. “It’s the most beautiful crazy hat and it’s so great that she wore a hat to a British premiere. The hat is such a quintessentially English idea, but it was done in such a Carrie Bradshaw way.” And yes, Parker gets to keep it.