Here are some examples of how to address holders of British honours and titles:

• The Queen is first addressed as “Your Majesty” and subsequently as “Ma’am”.
• A Royal Prince is first addressed as “Your Royal Highness” and subsequently as “Sir”.
• A Royal Princess is first addressed as “Your Royal Highness” and subsequently as “Ma’am”.
• A Knight is addressed as “Sir” (eg "Sir John Smith"), and the wife of a Knight as “Lady” (eg "Lady Smith").
• An Ambassador is addressed as “Your Excellency”.