Caps of Maintenance is a ceremonial crimson velvet cap lined with the skin and fur of an ermine. It is one of the insignia of the British sovereign, and paraded directly before the monarch during the coronation procession or on such state occasions as the State Opening of Parliament. It is carried by the Leader of the House of Lords, upon a white wand.
A similar cap is used throughout British heraldry, and is worn inside the coronets of Lords. For this reason, it is also borne before the Lord Mayor of the City of London and Lords Mayors of other cities.
The origin of this symbol of dignity is obscure. It may have had a purely practical origin being used to help a crown fit more firmly or to protect the head from bare metal on the crown.
According to the Oxford English Dictionary it was granted by the Pope to Henry VII and Henry VIII. It is probably connected with the cap of estate or dignity, sometimes also styled Cap of Maintenance, similar to the royal symbol with two peaks or horns behind, which is borne as a heraldic charge by certain families. It seems originally to have been a privilege of dukes. Where it is used the crest is placed upon it, instead of on the usual wreath.