In fashion, almost everything is decoration: embroidery for beauty, a button for effect, a colour for the season. On 26 September, Denmark's Queen Mary wore a jacket where it's the other way round. Not a single detail on it is there to look pretty - each one marks a rank, an order or an institution.

Mary accompanied King Frederik X to the gala dinner for the Army's badge of honour, at Christian VII's Palace in the Amalienborg complex. For the occasion she wore the Danish armed forces' women's full-dress uniform, which she presented in January 2019, while she was still Crown Princess. Back then it was one of the first public appearances of the new uniform designed specifically for women in the army and the other defence services.

The centrepiece is a fitted black jacket in satin wool, with gold embroidery of oak leaves and floral motifs. It isn't an ordinary blazer: it's regulation dress, worn over a long formal gown. Rather than covering the gown, the black structure frames the torso and pulls all the attention to the chest - where the decorations sit.

And the decorations are a story in themselves. Mary wears military medals and the insignia of the Danish royal orders, including the star of the Order of the Elephant and the badge of the Order of the Dannebrog. The Order of the Elephant is Denmark's oldest and most prestigious order of chivalry: its roots lie in a brotherhood founded by Christian I around 1460, it received its statutes in 1693 under Christian V, and the elephant with a tower on its back became its symbol when Frederik II revived it in 1580. The light blue sash running from the left shoulder belongs to the same order.

The jacket is the same as in 2019, but the woman wearing it isn't. In 2008 Mary joined the Danish Home Guard as a private and began military training. In 2009 she was made sergeant and second lieutenant, in 2015 first lieutenant, in 2019 captain, and in May 2023 she became an honorary major. The same uniform is now worn by a queen with a long military career.

The evening has its own history too. The Army's badge of honour was introduced on 26 September 1945, for those who had completed 25 years of service in the armed forces. The date is the birthday of King Christian X, born on 26 September 1870 - Frederik X's great-grandfather. The dinners rotate between the Army, the Navy and the Air Force, so the Army's comes round roughly every three years. This year Christian X's Honour March was also played at the banquet.

The Danish monarchy is a master of exactly this - objects, orders and ceremonies passed down through generations without losing their meaning. The black, the gold embroidery, the blue sash and the stars aren't fashion choices; they're documents. How many of our institutions have a ritual that has survived 81 years without someone wanting to reinvent it from scratch?