Other Members of the Royal Family
Only close personal friends are expected to write to members of the Royal Family direct. All other correspondents should write to the private secretary of the member of the Royal Family in question. In this way the letter may be worded quite simply, without having recourse to the elaborate forms of address required for direct communication with the Sovereign, the Prince of Wales and other members of the Royal Family.
If you are in any doubt about the correct protocol for any royal event to which you have been invited, refer to the appropriate royal household for advice. Enquiries should be addressed to the private secretary.
Be aware that certain conventions rule the ways in which members of the Royal Family are addressed - both in conversation and in writing. While it is strongly advised that the established forms of address (for example, 'Your Majesty/ma'am; Your Royal Highness/Sir') are strictly adhered to for the senior members of the Royal Family, it is probably advisable for anyone who is due to meet the younger princes or princesses for the first time to consult with their office to find out what level of formality might be expected.
Meeting members of the Royal Family is often within a formal context, and dress codes - always specified on the invitation - apply:
Morning dress: For men this consists of a grey or black morning coat, with a grey or yellow waistcoat and striped grey trousers. A top hat should be worn and gloves - matching the waistcoat should be carried.
For ladies this dress code means smart day dress - a suit or dress (with jacket), with hat and gloves, high heels and a matching handbag.
Lounge suits: For men, a plain business suit, worn with a discreet collar and tie.
For ladies, smart day dress is again the norm.
Black tie: For men, a dinner jacket and bow tie.
For ladies, an evening or cocktail dress (avoid black, which is only appropriate when the Court is in mourning).
White tie: For men, an evening tail coat with white bow tie and waistcoat.
For ladies, a full length evening dress, worn with long gloves and jewellery (including tiaras)