A 17th-century silk dress reportedly belonging to someone on the royal court of an English queen was found buried in sand on a Dutch island.

The Dutch News reported Thursday the dress belonged to someone who was on the royal court of English Queen Henrietta Maria. The queen was apparently traveling on a secret mission in the Wadden Sea when one of her baggage ships sank.

According to paper, the queen’s trip to the Dutch Republic was to deliver her 11-year-old daughter to the court of William II, Prince of Orange – whom the girl married a year before the delivery.

However, the trip was apparently a cover for a secret mission.

The mission was to sell the crown jewels and use the money to buy weapons for King Charles I. A pivotal move because the king needed the weapons in the English Civil War.

Experts at Leiden University and the University of Amsterdam confirmed the authenticity of the dress, the Dutch News reported.

The gown is well preserved and was on display at the Texel maritime museum earlier in April.

The dress was found with a book inscribed with the British house of Stuart’s coat of arms, which led researchers to link the dress to British royalty.

Historians believe the dress belonged to the Countess of Roxburge, Jean Kerr.

Kerr was a confidant of the queen and was one of two women who lost baggage from the ship sinking. Researchers based the link from the style and size of the gown as well as a letter from Elizabeth Stuart to Sir Thomas Roe who wrote about how her sister-in-law lost her baggage during the crossing in 1642.

Helmer Helmers from the University of Amsterdam and Nadine Akkerman from Leiden University said they were able to solve the dress’ mystery fairly quickly.

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