The stunning red dress Kate wore for the Queen’s Diamond Jubilee became such a hit with fans that it had already sold out on fashion websites.
The Duchess of Cambridge modelled an adapted frock by Alexander McQueen designer Sarah Burton, for the big day.
But it is understood that Kate copied the look after X Factor judge Tulisa and reality telly star Kim Kardashian both donned the dress on different occasions last summer, the Daily Star reported.
She liked the look so much she secretly tucked it away for the Jubilee and asked designers for a modified version with sleeves and a longer skirt.
Sexy Tulisa wore a sleeveless version of the dress on her birthday while Kardashian was spotted in the same outfit as she filmed scenes for her reality show in New York in September.
Fashionistas praised Kate’s regal dress sense and choice of outfit, with fans on Twitter describing her look as “stunning”.
Style queen Sarah, who designed the red frock for the McQueen brand, also created Kate’s famous wedding dress last year.
The royal also wore a red hat designed by Sylvia Fletcher for James Lock and a pair of her trademark beige heels, along with a silver dolphin brooch that was a gift from Prince William.
The design had sold out as Kate’s fans stormed fashion websites, despite its 1,200-pound price tag.