King calls for unity in first Commonwealth Day speech as protesters gather at Westminster Abbey
King Charles has given his first Commonwealth Day address as monarch against the backdrop of protests at Westminster Abbey.
The King urged the family of nations to "strive together" for the "global common good" at the annual service celebrating the Commonwealth.
Other royals at the service included the Queen Consort, the Prince and Princess of Wales, the new Duke and Duchess of Edinburgh, the Princess Royal and the Commonwealth Secretary-General Baroness Scotland.
They were joined by faith leaders, school children and dignitaries from across the UK and the Commonwealth.
Since the death of the Queen, a number of Commonwealth nations - including Antigua and Barbuda, Belize and The Bahamas - have signalled they could kickstart plans to hold referendums on whether the monarch should remain head of state.
But Charles said the institution still played an "indispensable role in the most pressing issues of our time", including on climate change, education and economic cooperation.
He also paid tribute to his "beloved mother" whom he said had dedicated her "long and remarkable life" to the "Commonwealth family", which currently comprises 56 independent countries.
In his speech, the King said: "Whether on climate change and biodiversity loss, youth opportunity and education, global health or economic cooperation, the Commonwealth can play an indispensable role in the most pressing issues of our time.
"Ours is an association not just of shared values, but of common purpose and joint action.
"In this we are blessed with the ingenuity and imagination of a third of the world's population, including one and a half billion people under the age of 30.
"Our shared humanity contains an immensely precious diversity of thought, culture, tradition and experience. By listening to each other, we will find so many of the solutions that we seek."
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The King, who is the head of the Commonwealth, delivered his speech in person from the great pulpit in Westminster Abbey, in contrast with the Queen who sometimes pre-recorded her message.
A handful of protesters gathered outside during the event, with some carrying placards emblazoned with the words: "Not my King".
But Charles sought to project an image of unity, telling the audience: "The myriad connections between our nations have sustained and enriched us for more than seven decades. Our commitment to peace, progress and opportunity will sustain us for many more.
"Let ours be a Commonwealth that not only stands together, but strives together, in restless and practical pursuit of the global common good."
The King's coronation will take place at Westminster Abbey on 6 May.