Royal fans are convinced this clip of the Cambridges at play reveals Prince William's affectionate nickname for his daughter Charlotte.
The video, released by Kensington Palace on Instagram, shows the royal father-of-three with his wife Kate, 37, and their three children in the Duchess' Back To Nature garden at the Chelsea Flower Show last Sunday.
While most of the clip is subtitled, there is one short section of William speaking to Charlotte while on the rope swing that is missed out.
Dozens of social media users took to the comment section to say they think William calls his daughter "mignonette". The word is a diminutive form of the French "mignon", meaning "cute".