Wizards at large in the Muggle community may reveal themselves to each other by wearing the colours of purple and green, often in combination. However, this is no more than an unwritten code, and there is no obligation to conform to it. Plenty of members of the magical community prefer to wear their favourite colours when out and about in the Muggle world, or adopt black as a practical colour, especially when travelling by night.
The International Statute of Secrecy laid down clear guidelines on dress for witches and wizards when they are out in public.
When mingling with Muggles, wizards and witches will adopt an entirely Muggle standard of dress, which will conform as closely as possible to the fashion of the day. Clothing must be appropriate to the climate, the geographical region and the occasion. Nothing self-altering or adjusting is to be worn in front of Muggles.
In spite of these clear instructions, clothing misdemeanours have been one of the most common infractions of the International Statute of Secrecy since its inception. Younger generations have always tended to be better informed about Muggle culture in general; as children, they mingle freely with their Muggle counterparts; later, when they enter magical careers, it becomes more difficult to keep in touch with normal Muggle dress. Older witches and wizards are often hopelessly out of touch with how quickly fashions in the Muggle world change; having purchased a pair of psychedelic loon pants in their youth, they are indignant to be hauled up in front of the Wizengamot fifty years later for arousing widespread offence at a Muggle funeral.
The Ministry of Magic is not always so strict. A one-day amnesty was announced on the day that news broke of Lord Voldemort’s disappearance following Harry Potter’s survival of the Killing Curse. Such was the excitement that witches and wizards took to the streets in their traditional clothes, which they had either forgotten or adopted as a mark of celebration.
Some members of the magical community go out of their way to break the clothing clause in the Statute of Secrecy. A fringe movement calling itself Fresh Air Refreshes Totally (F.A.R.T.)* insists that Muggle trousers ‘stem the magical flow at source’ and insist on wearing robes in public, in spite of repeated warnings and fines.** More unusually, wizards deliberately adopt laughable Muggle confections, such as a crinoline worn with a sombrero and football boots.***
By and large, wizard clothing has remained outside of fashion, although small alterations have been made to such garments as dress robes. Standard wizard clothing comprises plain robes, worn with or without the traditional pointed hat, and will always be worn on such formal occasions as christenings, weddings and funerals. Women’s dresses tend to be long. Wizard clothing might be said to be frozen in time, harking back to the seventeenth century, when they went into hiding. Their nostalgic adherence to this old-fashioned form of dress may be seen as a clinging to old ways and old times; a matter of cultural pride.
Day to day, however, even those who detest Muggles wear a version of Muggle clothing, which is undeniably practical compared with robes. Anti-Muggles will often attempt to demonstrate their superiority by adopting a deliberately flamboyant, out-of-date or dandyish style in public.
* President Archie Aymslowe
** To date, they appear to have been taken as cult members by Muggles.
*** These are generally taken by Muggles to be students on a dare.