In the complex stratified hierarchy of the English peerage, 'Your Grace' serves as the distinctive style for those holding the highest secular title below the blood royal: the rank of Duke. Unlike lower grades of the peerage—Marquesses, Earls, Viscounts, and Barons—who are collectively addressed as 'My Lord,' a Duke is uniquely accorded this honorific. The style is also extended to their female counterparts, Duchesses, and maintains a dual significance within the Church of England, where it is the mandatory address for the Archbishops of Canterbury and York.
Historically, the term carried a more fluid application. Prior to the reign of King Henry VIII, 'Your Grace' was frequently used to address the Sovereign, alongside 'Your Highness.' As Tudor monarchs increasingly adopted 'Your Majesty' to reflect imperial pretensions and absolute sovereignty, 'Grace' was gradually ceded and solidified as the exclusive prerogative of the ducal rank and the high prelacy. In a heraldic and ceremonial context, the style reinforces the Duke's status as a 'high and mighty prince,' a vestige of the era when dukedoms were often synonymous with semi-autonomous territorial jurisdictions.