HOW DO I WRITE TO THE QUEEN OR A MEMBER OF THE ROYAL FAMILY, OR BEHAVE WHEN I MEET THEM?

Lots of people ask this question. There are no obligatory codes of behaviour - simply courtesy.

For more formal correspondence, people write to The Queen with the formal opening 'Madam' and close the letter with the form 'I have the honour to be, Madam, Your Majesty's humble and obedient servant'. For other members of the Royal Family the formal opening is 'Sir' or 'Madam'. Other people prefer to open their letter with 'Your Majesty' or 'Your Royal Highness' and end it with 'Yours sincerely'.

There are also no obligatory codes of behaviour when meeting The Queen or a member of the Royal Family. Many people wish to observe the traditional forms. For men this is a neck bow (from the head only) whilst women do a small curtsy. Other people prefer simply to shake hands in the usual way. On presentation to The Queen, the correct formal address is 'Your Majesty' and subsequently 'Ma'am'. For male members of the Royal Family the same rules apply, with the title used in the first instance being 'Your Royal Highness' and subsequently 'Sir'. For other female members of the Royal Family the first address is conventionally 'Your Royal Highness' followed by 'Ma'am' in later conversation.

Forrás:
www.royal.gov.uk