The primary duty of this office was carrying on the monarch's official correspondence, but in varying degrees the holder also advised the Crown, and by the early fourteenth century, the position was in effect the third most powerful office of state in England, ranking after the Lord Chancellor.

The Privy Seal's warrants increased rapidly in quantity and frequency during the late Middle Ages.

The Signet warrant, kept by the Keeper of the Privy Seal, could be used to stamp documents on authority of chancery and on behalf of the Chancellor.

Its controller was the Secretary, who served on military and diplomatic missions; and the Wardrobe clerks assumed an even greater importance.

Following the Glorious Revolution of 1688, the Cabinet took over the practical direction of affairs previously undertaken by the Privy Council, and the two secretaries of state gained ever more responsible powers.