The College of Arms, situated in Queen Victoria Street, near St Paul's Cathedral, is part of The Queen's Household and is under the authority of the Earl Marshal (one of the Great Officers of State).

Applications for a Coat of Arms are first submitted to the Earl Marshal (the Duke of Norfolk), who authorises every new grant of arms by issuing a warrant to one or more of the three senior heralds: Garter King of Arms, Clarenceux King of Arms, and Norroy and Ulster King of Arms.  One of the Kings of Arms or one of the other heralds is then responsible for the actual design of the Coat of Arms.

It is usual for the wife of a Royal Prince to have her own arms, and it is therefore no surprise that Catherine Middleton's father, Michael Middleton, wished to apply for a grant for his family. The design released by the College of Arms was approved and agreed by Thomas Woodcock, Garter King of Arms, in consultation with the Middleton family.

Catherine Middleton's Coat of Arms is presented on a 'lozenge' rather than on a shield, in deference to the female sex not generally being of a warlike disposition. In layman's terms the lozenge is divided vertically with one half blue and the other half red, crossed by a gold chevron (an inverted 'V' shape), with white lines on either side of the chevron, and three representations of a gold acorn on a leaved sprig, two above the chevron and one below.

The technical heraldic description (known as a blazon) is: Per pale azure and gules a chevron or cotised argent between three acorns slipped and leaved or.

After her marriage, Catherine Middleton placed her father's arms beside those of Prince William in what is known as an impaled Coat of Arms. This required a Royal Warrant from The Queen.

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