The vendor's uncle is James Ware, who worked as production manager on Charade. The vendor met Audrey Hepburn on the set in Paris and as they were the same dress size, her uncle purchased this outfit for her at the end of filming.
This outfit is worn in one of the film's key sequences as Reggie begins to realise what she has been drawn into, by the murder of her husband, by his war-time accomplices. Hepburn wears the outfit in the scene when she and Cary Grant go to the Black Sheep Club where she encounters the first of her husband's accomplices, Herman Scobie played by George Kennedy. He threatens her and scares her into running to a phone box to call who she thinks is a CIA officer in Paris, Mr Bartholemew played by Walther Matthau, but who is infact the murderer. In the phone box she encounters another of the accomplices, Tex Panthollow played by James Coburn, who threatens her by throwing lit matches in her lap - a small burn mark can be seen on the front of the skirt, which Hepburn pointed out to the vendor explaining how it got there.