Beatrice opted for a purple satin corset dress and cross necklaces while her sister Eugenie plumped for red with a silver sequinned bolero, colour clash nail polish and a Union flag ring.
Given that the dress code at the party was essentially 'fun' (neatly encompassing classy, trashy, drag, and moustaches - :D ) we're not going to evaluate the princesses' style except to ask why neither of them have donned a 'tache for the event. What gives, ladies?
We're also kind of wondering whether the princesses attended thinking it was a party for THE Queen rather than someone FROM Queen. Either way, they got into the spirit of things.
To see the princesses in action at a different Queen-related event (tenuous? Us?) just click through our royal wedding gallery below: