Britain's Prince William and his wife Catherine, Duchess of Cambridge take part in Canada Day celebrations on Parliament Hill in Ottawa, July 1, 2011. [Photo/Agencies]

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OTTAWA, Ontario - Prince William and Kate joined in Canada Day celebrations on Friday, often stealing the show as they were feted by Canadian leaders and cheered by tens of thousands who lined the streets of the Canadian capital to get a glimpse of them.

Canadian Prime Minister Stephen Harper welcomed them to an afternoon program at Parliament Hill as "the world's most famous newlyweds" and said they represent "our unbreakable link with our past and our unqualified optimism for the future."

The crowd - many dressed in Canada's red and white colors - exploded in prolonged cheering and chants of "Will and Kate, Will and Kate." A few wore homemade crowns in a nod to the royals.

The royal couple, who married in April and are on their first official overseas tour, beamed.

In his speech marking Canada's 144th birthday, the prince talked of his and Kate's family ties to Canada - in French and English, as he had a day earlier.

He said that Kate had learned about Canada from her late grandfather, "who held this country dear to his heart for he trained in Alberta as a young pilot during the Second World War."

On his side, he spoke of his grandmother, Queen Elizabeth II. The queen, he said, "has asked me to convey her warmest good wishes to the people of Canada, and her happy and abiding memories of being on Parliament Hill with Thee Duke of Edinburgh one year ago."

The prince referred to his grandmother as "the queen of Canada," since she remains Canada's head of state, drawing a loud cheer from the crowd. He said the queen was watching their Canada tour with interest.

Kate wore the same dress that she wore in her official engagement photos, a cream-colored dress from London designer Reiss. But for her Ottawa appearance, she added the queen's Maple Leaf brooch and a brilliant red hat topped with a maple leaf. The queen loaned the brooch to the duchess for the tour; it was first worn in 1951 by the then-Princess Elizabeth on her first visit to Canada. Prince William wore an understated blue suit and a red tie.

Police estimated that some 300,000 people were gathered around Parliament Hill to watch the Canada Day show.

A 21-gun salute to Canada's and military plane flyovers were part of the pageantry. When two F-18's did a flyby, Kate mouthed "that scared me" and put her hand to her heart.

At breaks in the official program, the crowd erupted into the cheer "Will and Kate, Will and Kate." There also were cheers of "Prince William, Prince William," suggesting that the young prince was charming his Canadian audience as much as his new bride was.