Very rarely does it seem that the royal family can do something without the whole world knowing, but somehow Prince William and Kate Middleton managed to do so -- at least for a few hours. 

The Duke and Duchess of Cambridge hosted Bill and Melinda Gates at Kensington Palace on Tuesday. Although the meeting was not announced beforehand, it was recorded in the Court Circular, the daily record of royal engagements.

According to Hello, the billionaire philanthropists were meeting at the London residence "in their role as patrons" to the Royal Foundation -- Gates is co-chairman and trustee of the Bill and Melinda Gates Foundation, the largest foundation in the world which boasts billions of dollars given to charity. 

READ: Kate Middleton Confronted Prince William After He 'Humiliated' Her Amid Cheating Rumors

The Gates' visit was probably a welcome distraction for William and Kate, whose relationship was tested earlier this year with a cheating scandal. 

Many fans of the royal family believe that the alleged infidelity was simply made up to sell tabloids, after all, no proof has ever emerged of the claim. Despite the lack of evidence, though, Gwendolyn Hendrix McGregor Scherer, a former professor, believes where there's smoke there is fire. 

"One reason I think this may have happened is Will’s lack of experience with the opposite sex. Though he broke up with Catherine a couple of times to 'give himself space' and date others (mostly of his class) he claimed, and his escapades with his friends while on a skiing trip, also tells me that Will should have spent more time getting to know other women," she said.

Prince William and Kate Middleton Prince William and Middleton meet with Irish Guards after attending the St Patrick's Day parade at Cavalry Barracks on March 17, 2019 in Hounslow, England. Photo: Getty Images/Gareth Fuller