A royal warrant of precedence is a warrant issued by the monarch of the United Kingdom to determine precedence amongst individuals or organisations.
Most warrants of this type are issued to grant a rank to a member of the nobility or gentry that they would normally have enjoyed when their relative (usually their sibling) inherits a title, but failed to assume automatically due to such circumstances as the death of their father (see courtesy title). The warrants are usually issued to the following effect:
The King/Queen has been pleased to ordain that <name> shall henceforth have, hold and enjoy the title, rank, place, pre-eminence and precedence as the younger son/daughter of a duke/marquess/earl etc. which would have been due to him/her had his/her father, <name>, survived his <e.g. brother>, <name and title>, and thereby succeeded to the said title and dignity of Duke/Marquess/Earl etc. of Somewhere. And to command that the said Royal Concession and Declaration be recorded in His/Her Majesty's College of Arms [and also in His/Her Majesty's Lyon Office if a Scottish title].
Below is a list of such warrants in descending order of rank (note: the Orders of Precedence for males and females are separate from one another):