STORY: King Charles reflected on the life of his mother in an address shared on Tuesday (April 21), marking what would have been the late Queen Elizabeth's 100th birthday.

Elizabeth, Britain's longest-reigning and longest-lived monarch, was born on April 21, 1926, going on to spend 70 years on the throne before her death in September 2022 at the age of 96.

Such is her enduring impact that a YouGov survey last week found that 81% of those polled had a positive opinion of her, more than any living member of the royal family.

"Her near century was one of remarkable change, and yet through each passing decade, through every transformation, she remained constant, steadfast, and wholly devoted to the people she served," Charles' said.

"Much about the times we now live in, I suspect, may have troubled her deeply, but I take heart from her belief that goodness will always prevail and that a brighter dawn is never far from the horizon," he added.

To mark the anniversary of her birth, Charles and Camilla visited a new exhibition, "Queen Elizabeth II: Her Life in Style", which is currently being held at Buckingham Palace.

More than 300 items, ranging from the late queen's wedding dress to the outfit she wore for her cameo appearance at the opening of the London 2012 Olympics, are on display in the largest-ever exhibition of her wardrobe.

Famed for wearing bright colours and matching hats, she once quipped: "I have to be seen to be believed."

On Tuesday, the king and other royals will visit the British Museum to view the final designs for a national memorial to his mother, while Charles' sister, Princess Anne, will officially open the Queen Elizabeth II Garden in London's Regent’s Park.

In the evening, Charles and Camilla will host a reception featuring representatives from charities his mother supported as well as a number of people who will be celebrating their 100th birthday.

The royals' commemorations come after the government announced on Sunday (April 19) that a new independent charity, the Queen Elizabeth Trust, was being launched to focus on restoring shared spaces in communities, backed by 40 million pounds ($54 million) with the king as its patron.

DESCRIPCIÓN DE IMÁGENES

REFILE: Britain's King Charles pays tribute to Queen Elizabeth II on what would have been her 100th birthday

VIDEO SHOWS: ADDRESS BY BRITAIN'S KING CHARLES MARKING WHAT WOULD HAVE BEEN HIS MOTHER, QUEEN ELIZABETH'S 100TH BIRTHDAY

EDITORS PLEASE NOTE: REFILING TO UPDATE SHOTLIST WITH RESTRICTIONS ADDED

SHOWS: LONDON, ENGLAND, UNITED KINGDOM (RECENT) (ROYAL FAMILY - No use UK / Must on-screen credit 'Royal Family' / No use after April 20, 2027)

1. (SOUNDBITE) (English) BRITAIN'S KING CHARLES, SAYING: (SOUNDBITE CONTINUES OVER VARIOUS SHOTS OF KING CHARLES)

"Today, as we mark what would have been my beloved mother's 100th birthday, my family and I pause to reflect on the life and loss of a sovereign who meant so much to us all, and to celebrate anew the many blessings of her memory. Queen Elizabeth's promise with destiny kept, shaped the world around her, and touched the lives of countless people across our nation, the Commonwealth, and beyond. Her near century was one of remarkable change, and yet through each passing decade, through every transformation, she remained constant, steadfast, and wholly devoted to the people she served. Millions will remember her for moments of national significance; many others for a fleeting personal encounter, a smile, a kind word that lifted spirits, or for that marvellous twinkle of the eye when sharing a marmalade sandwich with Paddington Bear in the final months of her life. Much about the times we now live in, I suspect, may have troubled her deeply, but I take heart from her belief that goodness will always prevail and that a brighter dawn is never far from the horizon. For, as a young Princess Elizabeth put it in her first-ever public broadcast, aged just 14, we could each play our part to make the world of tomorrow a better and happier place. It is a belief which I share with all my heart. So, young or old, and whatever our differences, let us therefore seek to follow this example as we make today not the marking of a milestone felt by absence, but the celebration of a life well-lived and a legacy of hope as we strive together towards a better, happier tomorrow, one rooted in peace, justice, prosperity, and security. In this, I renew my own solemn pledge of duty and service to you all. God bless you, darling mama. You remain forever in our hearts and prayers."