There were a few things going on at the time that I wrote to Camilla about, her upcoming Tour of the USA with Charles, & her 10th Wedding anniversary.
What is really interesting about this reply is it was sent by registered mail. This means it was tracked and I had to sign for it.
The Card inside is twice the size as the ones's usually sent by William, Catherine and Harry. The picture was originally released for an interview that Charles gave to CNN prior to the couple's tour of the USA in March.
The back of the card has a simple typed message, handed signed by Camilla herself. Camilla is well know for often writing back herself, or personally signing cards. I know a handful of people you have received personal responses from the Duchess.
The Green Monogram is used by Camilla for letters sent from Birkhall, Charles and Camilla's Scotland Residence.
A Blue Monogram is used for letters sent from Clarence House, their official residence in London.