Canada's Governor General was among the first international dignitaries to congratulate Prince William and his wife Kate on the birth of their son on Monday.
Shortly after the Twitter account of Clarence House, the royal couple's official residence, tweeted "Her Royal Highness The Duchess of Cambridge was safely delivered of a son at 4:24 p.m.," Gov. Gen. David Johnston replied: "Wonderful news!"
Johnson tweeted that he and his wife, Sharon, are "overjoyed to learn that the royal couple are the proud parents of a baby boy."
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Prime Minister Stephen Harper said the arrival of the newest member of the Royal Family and future sovereign of Canada is a "delight," and that he and all Canadians offer "heartfelt congratulations to the royal couple."
On Twitter, MP Justin Trudeau said, "Congratulations to the Duke and Duchess of Cambridge on the arrival of their first son!"
And on Parliament Hill, Ottawa will recognize the birth by illuminating Peace Tower with blue light. Toronto's CN Tower will do the same, as will Niagara Falls. The landmarks will be lit blue on Monday evening.
Minister of Heritage and Official Languages Shelly Glover told the CBC's Evan Solomon "the little prince is someone we anxiously wait to see," during an interview on Power and Politics with Evan Solomon.
Reaction around the world
U.S. President Barack Obama and his wife Michelle Obama congratulated the duke and duchess on the "joyous occasion of the birth of their first child," wishing them "all the blessings parenthood brings."
Prince Charles responded to news of the birth by saying he was "enormously proud" of becoming a grandparent for the first time.
"Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months," Charles said. Charles and Camilla, the Duchess of Cornwall, were on official duty in Yorkshire, some 320 kilometres from London on Monday.
U.K. Prime Minister David Cameron said he is "delighted" and that "a proud nation" welcome the news.
"Right across the country and indeed the Commonwealth, people will be celebrating," Cameron said.
A 62-gun salute is planned for Tuesday at the Tower of London and a 41-gun salute will follow in London's Hyde Park.
The Archbishop of Canterbury Justin Welby joined the well-wishers, posting one of the first congratulatory Twitter posts.
Welby said he was "delighted" for the duke and duchess. "May God bless them all with love, health and happiness," he tweeted.
The Royal Mint also recognized the birth, minting commemorative coins to be handed out to the first 2,013 parents of newborns who share today's royal birthday. The silver pennies, which feature a shield of the Royal Arms, will be presented in a blue or pink pouch to "anyone in the U.K. who welcomed a new arrival on the 22 July," according to a post on the Mint's Facebook page.
In London, crowds cheered outside St. Mary's hospital at news that Kate had given birth to an 8 lb., 6 oz. baby boy at 4:24 p.m. London time. The infant will become third in line for the British throne after Prince Charles and his father William, the Duke of Cambridge.
The royal birth recalled that of the baby's father, William, in 1982, at the same central London hospital. Many remember the moment when he was carried out in his mother Princess Diana's arms with proud father Prince Charles at their side.
Kate checked into a private wing at St. Mary's Hospital in central London early Monday morning. William spent the long hours of labour at her bedside, according to a statement.