As always, post your Royal Questions & I will get to them as soon as possible.
Question 1: Is this a good address?
Princess Anne's Office
London SW1A 1BA
Answer: Sort of...... If you are writing to Princess Anne I would just say "Princess Anne" not "Princess Anne's Office." I would only use "Princess Anne's Office" if you are writing to someone else at her office, like specifically to her staff, or her children whose letters get forwarded.
Also, the postcode is "SW1A 1AA" not "SW1A 1BA."
Question 2: What is the definitive difference between the first and second class letters from the British Royal Family?
Answer: In general, the main difference between 1st & 2nd class mail is how long it takes to arrive. 1st class mail is quicker (1 day for letter sent inside the UK). 2nd Class is a little slower (2-3 days for inside the UK). How long it takes with International mail will vary greatly.
The Royals use both 1st class & 2nd class mail for some different things. But I don't think they are very strict about what gets a 1st class vs. 2nd class stamp, as they envelopes aren't actually stamped by the Royal Office it comes from. Instead, all the mail from the different royal offices is collected by the Royal Mail and taken to the Court Post Office at Buckingham Palace. And it is there that the Royal Mail actually stamps/franks all the mail.
For international mail, the British Royals mostly use 1st class. For mail inside the UK, they tend to use 2nd class mail, except when the things is more special and they want to be sure it arrives on a certain date.
Question 3: Do you send your letters priority or as usually?
Answer: I'm from the USA. I send my mail 1st class, which is of the standard. I just buy a sheet of global forever stamp, which are good for international letters.
Question 4: Is it ok to just write my address only in the letter and write the royal address only on the envelope?
Answer: It's fine. But I would recommend writing it on both your letter and envelope.
Question 5: What address to Princess Caroline of Monaco?
Answer: You can find all the addresses for the Royal on our "Writing to the Royal" Tab. The address for the Monaco Royals is:
Palais de Monaco
Boite Postale 518
Monacode Cedex 98015
Question 6: I see that Queen Anne Marie of Greece is often in Denmark, can I write to her on the address of the Danish royal family? Would the letter be forwarded to her if she is in Denmark or anyway it will be forwarded in Athens or just thrown away?
Answer: I would not write to Queen Anne-Marie of Greece with the Denmark Royal's Address, even though she is a member of the extended royal family. Royals don't answer handle their own mail from the public, it's all done by certain people in their office. So, just because Queen Anne-Marie is in Denmark often doesn't really many anything in terms of her mail. The Denmark Palace may throw it out or may forward it. But either way, it would be much better to just send your letter directly to Greek Royal's office in Greece. Their address is:
145 03, Athens,
You can find the addresses for the different former Monarchies here.