Afterwards, the little Princess made a royal dash to the loo.
Her mum accompanied her as she nipped into the Phoenix in Stockwell to use the ladies.
One onlooker told The Mail, "It just goes to show that the royals are like any other family. When your kid needs to go to the loo, they got to go!"
Earlier this year, William revealed that dancing is Charlotte’s favorite hobby.
“My daughter Charlotte loves dancing,” he proudly told attendees at a Commonwealth Day reception.
And she's not the only Princess who does.
Taking to her official Instagram page, Princess Madeleine of Sweden posted a snap of her daughter Princess Leonore.
"Our very own Nutcracker ballerina!"