Prince William has paid a secret visit to Britain’s intelligence agency MI6.

The heir to the throne’s surprise engagement on Thursday afternoon was revealed through the Court Circular, a daily list of royal engagements published the day after they take place.

It simply states: “The Prince of Wales this afternoon visited the Secret Intelligence Service.”

No prior information was revealed ahead of the visit.

While nothing is known about the details of yesterday’s visit beyond the fact that it took place, this is not the first time that the Prince of Wales has visited the intelligence agency.

His last reported visit was in 2022 when he was still the Duke of Cambridge, and he previously visited the intelligence organisation’s headquarters in 2012 with his then-new wife, Kate Middleton.

MI6 is the UK’s secret intelligence service and its staff, including boss Sir Richard Moore, codenamed “C”, work behind the scenes to keep the country safe.

Prince William paid a secret visit to MI6 yesterday afternoon (REUTERS)

It is not the only intelligence agency in the UK either and there is also MI15. The difference between the two is that MI6 works within the UK while MI5 operates in other countries.

“These agencies are full of people from everyday backgrounds doing the most extraordinary work to keep us safe,” Prince William previously said.

“They work in secret, often not even able to tell their family and friends about the work they do or the stresses they face.”

The Prince’s visit interestingly came the same day Buckingham Palace announced that King Charles had appointed the first-ever female chancellor of the Order of the Garter, former director general of MI5 Baroness Manningham-Buller.

Baroness Manningham-Buller has been appointed to the role by the King (Chris Jackson/PA) (PA Archive)

It also comes ahead of tomorrow’s Trooping the Colour, which is one of the biggest events in the royal calendar.

The eyes of the world will be upon the Buckingham Palace balcony, in particular, following reports that the Princess of Wales is “considering” making a surprise appearance.

Should she do so, it will be the first time she has been seen in public since Christmas Day last year.

She took a step back from her duties for planned abdominal surgery in January before she subsequently revealed in a poignant video that she had been diagnosed with cancer and was undergoing “preventative chemotherapy”.

Her cancer announcement came following intense speculation about the Princess’s whereabouts, which were and still the subject of conspiracy theories.

The situation was exacerbated by a Mother’s Day photograph of Kate and her three children, which was pulled by major photo agencies over manipulation concerns.

A photograph of the Princess and her children was pulled by major photo agencies after it emerged that it had been doctored (Reuters)

Kate subsequently took responsibility for the blunder and described herself as an amateur photographer who does “occasionally experiment” with editing.

An official date for the Princess’s return to work has yet to be confirmed.

The Independent has reached out to Kensington Palace for comment.