This lovely reply arrived from the UK, back in October 2019.
The front of the envelope is the usual. The envelope features a double postmark. The first is the typical postmark from the Court Post Office at Buckingham Palace from that time. It also features a postmark from Mount Pleasant Mail Centre. The postmark is to celebrate the 50 years of Monty Python's Flying Circus.
The back of the envelope features Prince Andrew's badge. As Andrew's office was handling all of Princess Beatrice & Princess Eugenie's mail at the time, they used
Inside is a letter from Charlotte Fenn. The letter describes her job title as "Assistant Private Secretary to HRH Princess Beatrice of York." But officially, she was Prince Andrew's Assistant Private Secretary.
Princess Eugenie & Princess Beatrice didn't have any of their own staff members. But Prince Andrew's office does handle things for them.
The letter says:
Buckingham Palace8th August, 2019Dear Gertrude,
Princess Beatrice of York has asked me to thank you for sending her your good wishes on her Birthday. Her Royal Highness is very grateful to you for thinking of her and sends you her best wishes.
Yours Sincerely,Charlotte FernAssistant Private Secretary to HRH Princess
Beatrice of York