Act I – Scene.iv
At the palace, King Duncan gives official thanks to
Macbeth and Banquo and then announces that his successor as King will be his son, Malcolm, who is named hereafter as the Prince of Cumberland. This comes as a surprise to Macbeth.
Clearly the King was unhappy and surprised at Cawdor’s
treachery, and he refers to Cawdor thus, “He was a gentleman on whom I built an absolute trust.”
Just then Macbeth enters the room, Shakespeare clearly working on his irony
Perhaps the King realizes that he should have put more trust in Macbeth, who
he now sees as a potential successor, although he names his son as heir to the throne, calling him the Prince of Cumberland.