On Friday they visited Caernarfon, North Wales, about 20 miles from where they lived in a farmhouse for nearly four years, while William was an RAF helicopter pilot.
Shortly after arriving in Caernarfon town center, they went on a brief walkabout, being cheered by well-wishers, many of whom waved the Welsh flag with its dragon motif.
Kate was effortlessly chic in a grey coat (a royal rewear!), and she braved the windy weather with her hair tied back in a sleek ponytail.
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The couple, both 33, have made it a key part of their public work. On Wednesday, Kate made a landmark speech to spotlight the cause at a conference supported by one of her key charities, Place2Be, where she noted that "the roots of poor mental health in adulthood are almost always present in unresolved childhood challenges."
They also met with a group of local Girl Guides and scouts, and Kate shared that she'd like for daughter Princess Charlotte to join the youngest group, Rainbows (for girls ages 5-7).
"She said that she needs to put Charlotte's name down for Rainbows," Caernarfon's county commissioner for Girl Guides, Jill Wilkinson, tells PEOPLE.
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"George would love the bubbles. We'll have to get him one for Christmas," he said.
In Caernarfon, the royal parents saw a photography project run by the local branch of mental health charity Mind and spend some time with a group that provides support and accommodation for local homeless youth.
Next, they are scheduled to take in the spectacular scenery of Snowdonia to see schoolchildren at an outdoor recreation center run by a mountain rescue organization, before ending the day at another facility run by Mind – this time a center for men, in Denbigh, about 50 miles from their first call of the day.