Baroness Patricia Scotland said the Queen was “an extraordinary person, who lived an extraordinary life”, adding that “the world will miss her greatly”.
She said the 96-year-old monarch’s life was one of service which will “echo through the ages”.
In a tribute on Thursday night, Baroness Scotland said: “Throughout her reign, and seven decades of extraordinary change and challenge, Her Majesty was the epitome of duty, stability, wisdom and grace.
“Her Majesty loved the Commonwealth, and the Commonwealth loved her. During her reign she travelled more than any monarch in history, visiting every part of our family of nations.
“Between 1971 and 2018, she missed only one Heads of Government Meeting. Her devotion to duty was only matched by her skill as Head of the Commonwealth of Nations, always a generous host and consummate diplomat.”
The secretary-general said the growth and vibrancy of the Commonwealth “is a credit to her and testament to her dedication, wisdom and leadership”.
She said: “In 1953 Her Majesty defined our family of nations as one which ‘bears no resemblance to the empires of the past. It is an entirely new conception, built on the highest qualities of the spirit of man: friendship, loyalty and the desire for freedom and peace. To that new conception of an equal partnership of nations and races I shall give myself heart and soul every day of my life.’
“Her Majesty’s vision for the Commonwealth at the beginning of her reign has been fulfilled, fuelled by her dedication and commitment.
“Inspired by her life of duty and service, the responsibility to ensure her vision endures is one we all now share.”
Baroness Scotland said she will always be grateful for the Queen’s “warmth and kindness”, adding: “Our interactions were a delight, and it was wonderful to see her passion and animation whenever discussing anything relating to the Commonwealth.
“Her long years of interaction and partnership with generations of world leaders and their people, particularly the young, gave her extraordinary insight, which brought ever-more life and meaning to her service.
“I will miss her greatly, the Commonwealth will miss her greatly, and the world will miss her greatly. We will never see her like again.
“On behalf of the Nations and Citizens of the Commonwealth, I express our profound sadness at her passing, our admiration for all that she was, and our enduring gratitude for all that she gave us. We send our prayers, love and heartfelt condolences to the entire Royal Family
“Hers was a life of service which will echo through the ages. We will be forever grateful.”