Since Prince George's birth in July, the Duchess of Cambridge has rarely been seen in public as she adjusts to life as a mother.
In September, Prince William and Kate spent their first night away their son to attend a black-tie awards ceremony.
The Duchess had previously made her first surprise public appearance since George's birth when she joined her husband as he started the Anglesey Coastal Ultra Marathon in August.
More top news
Spoilt with more springtime sunshine
Gwen Stefani was joined by two of Hollywood's biggest stars in the latest episode of James Corden's Carpool Karaoke.
Special 'baby boxes' allowing mothers to give away unwanted babies safely have been installed at fire stations in Indiana, USA.