From Le Grand Mogol

Mademoiselle Bertin emigrated to London during the Revolution, but her shop, Le Grand Mogol, on rue Saint-Honoré, remained open and continued to supply Marie Antoinette with ribbons, lace, alterations and the occasional item of clothing even while she lived (or was imprisoned, depending on how you look at it) at the Tuileries and beyond.  The milliner provided the mourning dress that Marie Antoinette wore after Louis XVI's execution and the dress she wore when she arrived at the Conciergerie where she'd wait for her own execution.