Kate wore a blue Jenny Packham dress with a hat by Lock and Co. and a maple leaf broach lent to her by Queen Elizabeth II for the Canada trip.
After the legislature event, the couple is scheduled to leave for Government House, the family's home base for the royal tour that will see them five B.C. communities - Victoria, Vancouver, Haida Gwai, Bella Bella, and Kelowna as well as two Whitehorse and Carcross, Yukon.
The pictures, including shots of her sister Kate plus Prince George and Princess Charlotte, were reported by The Sun and Daily Mail newspapers to have been stolen from Middleton's account.
Catherine (R), Duchess of Cambridge and with daughter Princess Charlotte of Cambridge.
They will visit Great Bear rainforest, experience First Nations culture and meet Syrian refugees who have recently arrived in Canada.
Prince William emerged from the plane holding the hand of Prince George, dressed in a light blue sweater.
It's just the third time 16-month-old Charlotte has appeared in public.
The duke and duchess last paid a visit to Canada in 2011 shortly after their wedding as part of their first joint overseas tour.
Britain's Prince William, Catherine, Duchess of Cambridge, Prince George and Princess Charlotte arrive at the Victoria International Airport on Saturday.
Kate and William-also looking sharp in a grey charcoal suit-made their way from Victoria to Vancouver (about 70 miles north, in British Columbia), via sea plane.
Holding Prince William's hand as he walked down the steps of the plane, the three-year-old then joined his parents meeting dignitaries including Canada's Prime Minister Justin Trudeau and his wife Sophie Gregoire, eventually waving at the cameras before getting into a auto.
"The warm welcome that you gave us at that important moment in our lives meant a lot to us - and we have never forgotten it".
On Sunday, William and Kate travel to Vancouver where their itinerary includes a visit to Sheway, a pregnancy outreach program for mothers struggling with drug and alcohol issues in the heart of the city's Downtown Eastside, a neighbourhood known for its extreme poverty, homelessness and drug addiction.
A Kensington Palace spokesman said: "The tour will see them take in everything from the bustling global city of Vancouver - population 2.5 million - to the emote and handsome Bella Bella, home to less than 2,000 people".
In his speech, William spoke of the trip's focus on causes he and Kate care about.
On Saturday, Prince William and his wife will also lay a wreath at the cenotaph in front of the legislature to honour Canada's military service, and the prince will address Canadians.
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