“In medieval times, King Edward III was so inspired by tales of King Arthur and the chivalry of the Knights of the Round Table that he set up his own group of honourable knights, called the Order of the Garter. Nearly 700 years later, the Order is the oldest and most senior Order of Chivalry in Britain. The Knights, now both male and female, used to be limited to aristocracy, but today they are chosen from a variety of backgrounds, in recognition for their public service.
The annual iconic Garter Day procession, where The Queen and the Knights process in grand velvet robes, glistening insignia and plumed hats, is one of the most traditional ceremonies in the Queen’s calendar.
Every June, a grand procession of the knights takes place at Windsor Castle, accompanied by a marching band and Officers of the Order, all in grand ceremonial dress.” https://www.royal.uk/order-garter