Rare dress from UK collection H&M

Love this dress, bought at designer vintage boutique in soho but can no longer fit into it and only wore it once. So many compliments. Beautiful unique pattern and quality is shocking considering the brand. May have been designer capsule collection. Fabric feels like thick silk and quality stitching and construction. Some makeup stains as noted in photos. UK sizing so though it says size 2, it’s more like a size 0