In a special message released as millions across the country prepare to gather in her honour during four days of tributes and street parties, the Queen said “many happy memories” would be formed during the festivities.
The nation’s longest reigning monarch, 96, said she hoped the Jubilee weekend would provide an opportunity to reflect on the achievements of the last 70 years.
And she spoke of looking to the future with “confidence and enthusiasm”.
The message comes at the start of the extended bank holiday weekend, with millions across the UK and Commonwealth joining together in celebration of Elizabeth II and her 70-year-reign.
Her upbeat words come as the country and the world attempts to recover from the impact of the devastating coronavirus pandemic.
The Queen said: “Thank you to everyone who has been involved in convening communities, families, neighbours and friends to mark my Platinum Jubilee, in the United Kingdom and across the Commonwealth.
“I know that many happy memories will be created at these festive occasions.
“I continue to be inspired by the goodwill shown to me, and hope that the coming days will provide an opportunity to reflect on all that has been achieved during the last 70 years, as we look to the future with confidence and enthusiasm.”
It was signed Elizabeth R.
The Queen’s official Platinum Jubilee portrait was unveiled along with her message, showing the monarch, looking contented and happy, photographed in her Windsor Castle home.
She is pictured sitting on a cushioned window seat, with the historic residence’s famous Round Tower visible in the distance.
With her hands resting on her lap and her hair curled in its familiar style, the Queen is dressed in a dusky dove blue Angela Kelly coat.
The shiny pearl and diamante scalloped beading, embroidered around the collar and front trim, is perhaps seemingly a nod to her historic Platinum anniversary.
The image was taken by photographer Ranald Mackechnie in the Victoria Vestibule in the Queen’s private apartments at Windsor.
The Queen, who at the age of 96 has mobility problems, has been pacing herself ahead of the commemorations.
The extended weekend begins with the traditional Trooping the Colour military spectacle today, involving more than 1,500 officers and soldiers and 350 horses from the Household Division.
In the evening, more than 3,000 beacons will be set ablaze across the UK and the Commonwealth.
There will be no ceremonial journey to the service of thanksgiving at St Paul’s Cathedral for the Queen tomorrow, and the monarch, if she attends, will use a different entrance rather than scaling the steep steps.
And the Queen’s planned visit to Epsom for the Derby on Saturday is off, with members of the royal family attending on her behalf.
Saturday is also the first birthday of the Duke and Duchess of Sussex’s daughter Lilibet.
In the evening, the BBC’s Party at the Palace – set on three stages in front of Buckingham Palace – will entertain a live crowd of 22,000 people and a television audience of millions.
The line-up includes Diana Ross, Queen + Adam Lambert, Alicia Keys, Nile Rodgers, Andrea Bocelli, Duran Duran, Bond composer Hans Zimmer, Ella Eyre, Craig David, Mabel, Elbow and George Ezra.
Charles and William are preparing to deliver public tributes at the concert to the Queen, who is due to be watching on television from Windsor.
On Sunday, millions will gather for patriotic street parties, picnics and barbecues, with more than 85,000 Big Jubilee Lunches being held across the UK.
The finale is the Jubilee Pageant through the streets of London, with a cast of 6,000 performers and close to 200 celebrities joining the carnival procession.
It is hoped the monarch will make a final appearance on the Buckingham Palace balcony to round off the weekend to see Ed Sheeran singing the national anthem with a choir made up of Britain’s “national treasures”.