King Charles Chooses Sweet Childhood Photo with Queen Elizabeth to Thank People for Condolences

King Charles III is thanking the public for the sympathies shared following the death of Queen Elizabeth.

The new King, 73, chose a poignant photo of himself and the late Queen to thank supporters for their condolence cards, as seen on Twitter Wednesday. The cream card with a black border was stamped with the new monarch's cypher, opening to show a vintage photo of Charles and the Queen at Balmoral Castle in 1952.

King Charles, then 3 ½, happily peeked out a window at the Scottish castle, his mother smiling over his shoulder and looking in the same direction in the distance. Queen Elizabeth died at Balmoral on Sept. 8 at age 96.

"It was so very kind of you to send me such a wonderfully generous message following the death of my beloved mother. Your most thoughtful words are enormously comforting, and I cannot tell you how deeply they are appreciated at this time of immense sorrow," the King wrote, signing off as "Charles R."

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The sovereign's new signature comes with his changed royal rank. The "R" after his name stands for "Rex," which means "King" in Latin, the traditional signature for the monarch dating back to the 12th century. When used by Queens, the "R" stands for "Regina," or "Queen" in Latin. During her reign, Queen Elizabeth signed official communications as "Elizabeth R."

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Likewise, Charles' new cypher, unveiled late last month, shows an interlocking "C" and "R" with a crown above.

Buckingham Palace's correspondence team has been hard at work since the death of the Queen. At the end of the month, the palace announced that it had received over 50,000 letters and messages of condolence, including 6,500 in just one day following the Queen's funeral on Sept. 19.

Lisa Sheridan/Studio Lisa/Getty Princess Anne, Queen Elizabeth and Prince Charles

The volume marks an influx of messages — before the late Queen's death, the palace got around 1,000 letters each week from members of the public with various queries or messages of good wishes.

Photos released by the palace show the correspondence team sorting through thousands of letters sent to King Charles III, Queen Camilla and other members of the royal family.

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According to the palace, all letters are carefully read. Responses are sent as the small team processes the thousands of items.