Barack and Michelle Obama attend the National Portrait Gallery in Washington DC for the unveiling of their official portraits. The works, which will hang alongside other presidential portraits in the gallery, were created by Kehinde Wiley and Amy Sherald.

Barack’s portrait was painted by Kehinde Wiley, an artist best known for his vibrant, large-scale paintings of African-Americans, in which the subjects sit in fantastic, often ornate settings. Michelle’s was painted by Amy Sherald, a Baltimore-based artist known for her vibrant use of colour and for giving her predominantly African-American subjects a greyscale skin tone.

Of course, the moment was significant for many reasons – its modernity, patronage of African-American art, bold use of colour, the flower-wall! – but also for the dress worn by Michelle Obama. The full-length style, which has a graphic sensibility which distinguishes it from traditional formal gowns, is just as much a part of the painting as the sitter.

The designer of the dress in question is a lesser-known American label called Milly, which has previously been worn by Michelle Obama on official engagements, as well as a roll call of celebrities including Beyoncé, Gwyneth Paltrow and Emily Blunt. It’s known for its accessible wardrobe staples, like statement sweaters and flouncy blouses or ruffled dresses with wraparound waists.

Milly is the brainchild of designer Michelle Smith, who studied at the Fashion Institute of Technology in New York before starting Milly in 2000 after working in Paris at prestigious houses including Christian Dior, Louis Vuitton and Hermès. As a result, her label revolves around a contemporary combination of American sportswear with Parisian elegance. It’s also a family affair – Smith’s husband, Andrew, is her business partner and her young children have often accompanied as she takes a bow with her at the end of her shows at New York Fashion Week.