Prince William Quietly Visited British Secret Service M16 in Latest Solo Engagement

The Prince of Wales' private outing was not announced in advance

Prince William paid an under-the-radar visit to the Secret Intelligence Service of the United Kingdom.

On June 14, the Court Circular — the official record of past royal engagements — revealed that the Prince of Wales, 41, visited the secret service known as M16 the day prior.

"The Prince of Wales this afternoon visited the Secret Intelligence Service," said the entry. No further details were disclosed.

According to the Court Circular, the heir to the throne most recently visited M16 on Feb. 23, 2022, the same day the Russian invasion of Ukraine began. However, the Daily Mail reported that the 2022 stop "was thought to have been long-planned."

In the spring of 2019, Prince William discreetly spent three weeks immersing himself in the operations of M16, the Security Service (M15) and the Government Communications Headquarters, his office announced after it wrapped. The royal was eager to learn more about the work of the United Kingdom’s Security and Intelligence Agencies, Kensington Palace said at the time.

Related: Kate Middleton Seen for First Time Since Cancer Announcement in New Photo, Says 'I Am Not Out of the Woods Yet'

"With the threat level for international terrorism in the U.K. set at SEVERE or above for the last five years, the Duke was keen to see first-hand the extraordinary work that staff across the Security and Intelligence Agencies do," the palace said about the program.

King Charles' eldest son also voiced his gratitude for the opportunity and the work of the forces.

"Spending time inside our security and intelligence agencies, understanding more about the vital contribution they make to our national security, was a truly humbling experience," Prince William said in a statement. "These agencies are full of people from everyday backgrounds doing the most extraordinary work to keep us safe… We all owe them deep gratitude for the difficult and dangerous work they do."

Related: How Prince William Is Doing Behind the Scenes as Kate Middleton Shares Health Update

Tomorrow, Prince William is expected at Trooping the Colour, the British Army's public celebration for King Charles' official birthday. On June 14, Kate Middleton confirmed that she will attend the epic event, which will be her first public appearance since announcing her cancer diagnosis in March and her first public outing with the royals since Christmas.

The Princess of Wales, 42, shared in a personal letter that she is "making good progress" as she undergoes chemotherapy, and Prince William has been there for his wife.

Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! 

"The Prince is pleased to see The Princess starting to engage with the work and projects that are important to her," a Kensington Palace spokesperson says. "He will continue to focus his time on supporting his wife and children while continuing to undertake his public duties."

For more People news, make sure to sign up for our newsletter!

Read the original article on People.