But Angelina Jolie is known to be the Duchess' most glamorous fan and has, of late, eschewed her signature Armani Prive and Versace to sport one of Kate's favourite designers, Jenny Packham.
And now Jolie has invited the Duchess to the Olympics party she is throwing alongside fiance Brad Pitt.
Channeling Kate: Angelina Jolie has invited fellow Jenny Packham devotee The Duchess of Cambridge to the Olympics party she is hosting in honour of Muhammad Ali
The party, to take place on 25 July, two days before the official Olympics party, is to be held in honour of sporting heavyweight Muhammad Ali.
The glamorous soiree is intended to raise funds for the couple's chosen charity, Sports for Peace.
Brangelina, who are currently renting in London while Jolie is filming for her movie, Maleficient (and rumoured to be moving to the UK on a more permanent basis) plan to throw open the doors to their £20 million townhouse for the mother of all after-parties.
A source told the Daily Mirror: 'The who’s who of British and American celebrity will be in attendance, and invitees have been ordered not to take any photos from their phones'.
Other invited a-listers include David and Victoria Beckham, Sharon Stone, Michael Douglas and Catherine Zeta-Jones and Prince Harry.
Whether Kate and William accept the invitation remains to be seen but one thing's for sure, if Kate does make an appearance, all eyes will be on the wardrobe choices of the event's two leading ladies