The King warned that the climate is “changing dangerously” as he took part in a ceremony to mark the Scottish Parliament’s “milestone” 25th anniversary.
Charles, who was accompanied by his wife Camilla, addressed MSPs at Holyrood, saying that “much has changed in our world” since the Parliament was established a quarter of a century ago.
He spoke about the “challenges we all share as inhabitants of a planet whose climate is changing dangerously, and whose biodiversity is being seriously depleted”.
But the King, who was dressed in a kilt for the occasion, said he hoped this would be “the beginning of the next chapter”.
His comments came in a speech where he spoke of the “uniquely special place” Scotland is for the royal family.
Praising Scotland’s “natural beauty” and the country’s “strength of character”, he added: “My late mother especially treasured the time spent at Balmoral, and it was there, in the most beloved of places, where she chose to spend her final days.”
He described the formation of theScottish Parliament in 1999 as being a “landmark” in the nation’s “long, rich and complex story”.
He said: “This Parliament has grown in its experience, in its ability to touch, and to improve the lives of so many individuals and communities throughout this great land.”
As they arrived at Holyrood on Saturday morning, the King and Queen were met by Holyrood’s Presiding Officer Alison Johnstone and Deputy Presiding Officers Liam McArthur and Annabelle Ewing.
The royal couple then greeted Holyrood’s party leaders – First Minister and head of the SNP John Swinney, Scottish Conservative leader Russell Findlay, Scottish Labour leader Anas Sarwar, Scottish Green co-leader Lorna Slater and Scottish Liberal Democrat leader Alex Cole-Hamilton.
Mr Swinney said the ceremony marked “25 years in which the Scottish Parliament has changed lives for the better”.
The First Minister, who was wearing a kilt in Ancient Hunter tartan in honour of his late mother – whose maiden name was Hunter, told how since its formation “this Parliament has been the voice of Scotland”.
Mr Swinney, who has served continuously as an MSP since the first Holyrood elections in 1999, spoke of the “unending possibilities of Scottish self government”.
He said: “For 25 years Scotland has grown in confidence as she raised up this new institution at her very heart.”
The First Minister continued: “This Parliament has been steadfast in its compassion for the most vulnerable in society, and full of aspiration for the advancement of all.
“In the next quarter century it is my hope that Scotland’s democratic institutions continue to evolve and break new ground.
“I hope Scotland will continue to shine as a beacon of enlightenment across stormy seas, a refuge for reason in the world, a wellspring of modern thought and creativity.”
Earlier, Ms Johnstone recalled the “excitement and aspirations of the people of Scotland” when the Parliament opened 25 years ago.
She told the King: “Your presence here today, as we mark this significant milestone, demonstrates your continuing commitment.
“We are grateful for the encouragement and counsel that we have received over these last 25 years from the late Queen and from you.”
With the Scottish Parliament building – which is now 20 years old – being sited across from the Palace of Holyroodhouse, the royal’s family’s residence in Edinburgh, the Presiding Officer added that she hoped they found their “relatively newish neighbours agreeable”.
At the end of the ceremony, the King and Queen spent time talking to some of the ordinary Scots who had been invited to the ceremony as “local heroes” by MSPs.
The couple then signed a visitor book in front of a picture of the late Queen Elizabeth II, who Charles was with at the opening ceremony for the Scottish Parliament in 1999.
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