All those titles of nobles can get a bit confusing and overwhelming. You have to know the proper form of address if you ever ran into one on your daily constitutional at St James. How embarrassing to make that social faux pas!
Let's review!
The King: Your Majesty and thereafter,
Sire
The Queen: Your Majesty and thereafter, Ma'am
The Prince of Wales and other princes: Your Royal Highness, and thereafter, Sir
Princess Royal and other princesses: Your Royal Highness, and thereafter, Ma'am
A grandchild of a Prince without a tile: Lord Firstname or Lady Firstname
Duke and Duchess: Your Grace
Marquess, Earl, Viscount, Baron, or Lord of Parliament: My Lord, Your Lordship or Lord X
Marchioness, Countess, Viscountess, Baroness: My Lady, Your Ladyship, or Lady X
Baroness in her own right: My Lady, Your Ladyship, Lady X, or Baroness X
Baronet and Knight: Sir or Sir Firstname
Baronetess in her own right and Dame: Madame or Dame Firstname
Baronet and Knight's wife: My Lady or Lady X
Lady (knighted): My Lady or Lady Firstname
Elder Sons of Dukes, Marquesses, and Earls: My Lord, Lord X
Heir-Apparent of a Scottish Duke,Marquess, or Earl: Sir, Master
Heiress-Apparent of a Scottish Duke, Marquess, or Earl: Madam, Mistress
Younger sons of a Duke: My Lord or Lord Firstname
Younger daughters of a Duke: My Lady or Lady Firstname
Earl's younger son and sons of viscounts, barons, and the Lord of Parliament (Hon. titles): Sir or Mr. X
Earl's younger daughter and daughters of viscounts, barons, and the Lord of Parliament (Hon. titles): Madam or Miss/Mrs. X
Easy right? Oh but wait, it looks like some of the clergy are also enjoying the weather. Do you know the proper form of address for them? It would be awful to insult a man of the cloth.
Archbishop: Your Grace, Archbishop
Bishops: My lord, Bishop
Dean, Provost, Archdeacon, Prebendary, or Canon: by their titles (ie: Provost)
Priest: Mr. X or Father
Deacon: Deacon or Mr. X