Proper etiquette demanded not only seating persons by their rank, but addressing them correctly. If one not of the “manner born” managed to travel in the highest circles, one slip of the tongue could betray one’s formerly common social status. As owners of a grand house like Downton Abbey, the Earl and Countess of Grantham would entertain visitors quite often, and knowledge of the correct forms was vital (particularly for the Countess, who is American by birth).
Bates, Lord Grantham’s new valet, would address his employer as “My Lord” or “Your Lordship”.
The Duke of Crowborough would address the earl as “Lord Grantham”.
The countess would address her new guest as “Duke”, and he would address her as “Lady Grantham,” since they are of equal social status.
The duke would address the earl’s daughters as “Lady Mary, Lady Edith, and Lady Sybil”, and they would also address him as “Duke.”
As a servant, Thomas would address the duke only as “Your Grace.”
Anna would address the earl’s daughters as “My Lady” or “Your Ladyship.”
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