In theory what one may wear is governed by “Acts of Apparel”, detailed regulations with the force of law. Thus only Knights of the garter and persons of the rank of Earl and above, for example, are supposed to wear cloth of gold or silver or purple silk. There are exemptions for gentlemen actually in attendance on the Queen or serving on a foreign embassy or having a disposable income of at least 200 pounds a year. In practice, outside a royal court, these rules are widely ignored.
