Prince William on Thursday visited the Security Service, MI5, at its Thames House headquarters in London, according to a senior royal correspondent.
No pictures of the Duke of Cambridge's visit was shared on the social media accounts of the royal family.
Last month, Chief of MI6, the UK Secret Intelligence Service Richard Moore, said his agency hosted Prince Charles as he shared a picture with the Prince of Wales.
Meanwhile, Prince William and Kate Middleton attended the National Service of Remembrance with members of The Royal Family at the Cenotaph this morning to pay their respect "for those who have served and continue to serve our nation|."