The Duchess of Edinburgh and Prince Edward have shared a personal detail in a new letter.
The couple's conjugal Coat of Arms, a special family signature, was stamped on a letter sent to LEAF Education.
This is a charity close to Sophie's heart, as the mother-of-two is their honorary president.
The duchess personally wrote the letter as an impact report for the organisation, and her signature was featured at the bottom.
Sophie and Edward tied the knot in 1999
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The Coat of Arms, which is made up of two shields, is steeped in family meaning.
Married royal couples are given a joint Coat of Arms, known as their "conjugal" Coat of Arms, when they tie the knot.
On the left is Prince Edward's side, which contains elements of his Coat of Arms which he was given at age 19.
On the right is the Rhys-Jones coat of arms, created for Sophie’s father before her royal wedding in 1999.
Prince Edward and Sophie perform duties on behalf of King Charles [left]
PA
Sophie's side is represented by a backwards-looking lion on a red and blue background, in tribute to her family's Welsh heritage.
The website explains: "The lion is said to refer to Sophie's ancestor, the Welsh warrior Elystan Glodrudd, Prince of Ferrig.
"The supporter is 'almost' a Welsh Dragon. The Wyvern, though, again brings a lot of blue to UK Royal Heraldry."
The words "Bagshot Park" were printed underneath the Coat of Arms on the letter.
Prince Edward and Sophie, Duchess of Edinburgh on their wedding day in 1999
PA
LATEST ROYAL NEWS:
Prince Edward and Sophie live in Bagshot Park with their two children
PA
This is the sprawling estate where the royal couple live with their two children, Lady Louise, 20, and James, Earl of Wessex, 16.
The £30million residence has 120 rooms, but it is not owned by Prince Edward.
Instead, the Duke of Edinburgh leases the property from the Crown Estate.
The couple have lived at the property for 20 years since their royal wedding in 1999.