Britain's Queen Elizabeth's Platinum Jubilee celebrations in London
Britain's Prince Charles and Camilla, Duchess of Cornwall leave after the National Service of Thanksgiving for the reign of Queen Elizabeth, held at St Paul's Cathedral during the Queen's Platinum Jubilee celebrations in London, Britain, June 3, 2022. Matt Dunham/Pool via REUTERS.

Prince Charles paid an emotional personal tribute to his mother, Queen Elizabeth, on Saturday during celebrations to mark her Platinum Jubilee, praising the monarch for uniting the nation and continuing to make history during her 70-year reign.

Charles spoke at a pop concert that opened with a comic sketch of the 96-year-old monarch having tea with Paddington Bear and tapping out the tune to the Queen anthem "We Will Rock You" on her china teacup.

Handout for Platinum Jubilee
Undated image of Britain's Queen Elizabeth and Paddington Bear having cream tea at Buckingham Palace taken from a film that was shown at BBC's Platinum Party at the Palace. Released June 4, 2022. Buckingham Palace/Studio Canal/BBC Studios/Heyday Films/PA Wire/Handout via REUTERS .

The heir-to-the-throne appeared towards the end of the concert at Buckingham Palace. As images of Elizabeth's reign were displayed on the walls, Charles, 73, said the Jubilee had given the country the chance to say thank you.

"You pledged to serve your whole life - you continue to deliver. That is why we are here," he said in a message to the queen, who was at her Windsor Castle residence outside London.

"You have met us and talked with us. You laugh and cry with us and, most importantly, you have been there for us, for these 70 years," he added, referring to the queen as "mummy".

Queen's Platinum Jubilee celebrations in Windsor
Revellers gather on The Long Walk during Britain's Queen Elizabeth II's Platinum Jubilee celebrations, in Windsor, Britain, June 4, 2022.

The Saturday festivities were among a number of Jubilee events that Elizabeth has missed because of "episodic mobility problems" that have caused her to cancel engagements recently.

The opening video with the fictional character Paddington had echoes of 2012 when the queen appeared with Britain's most famous fictional spy, James Bond, in a video for the opening ceremony of the London Olympics.

In the clip on Saturday, she told Paddington she always kept the Bear's favourite - a marmalade sandwich - in her ever-present handbag.

A palace spokesman said: "The opportunity to invite a famous bear to tea was just too much fun to miss."

Q+AL performs in London
Adam Lambert of the collaboration "Queen + Adam Lambert" performs with the Royal Marine drummers at Queen Elizabeth's Platinum Jubilee concert in front of Buckingham Palace, London, Britain June 4, 2022. Alastair Grant/Pool via REUTERS

Queen's "We Will Rock You" then opened the show before the cast of "Hamilton," Andrea Bocelli, Alicia Keys and Diana Ross performed in front of tens of thousands of people crammed around the palace, down the Mall grand boulevard and in a nearby park.

Platinum Party at the Palace to celebrate The Queen's Jubilee
Alicia Keys performs onstage during the Platinum Party at the Palace in front of Buckingham Palace in London, Britain, June 4, 2022. Jeff J MitchellPool via REUTERS

Charles and wife Camilla; son William, wife Kate and their two eldest children sang along with the crowd before an aerial drone light show projected images into the sky, including the monarch on a stamp and the outline of her dogs.

BBC Platinum Party at the Palace to celebrate the Queen's Platinum Jubilee
Queen + Adam Lambert perform at the BBC Platinum Party at the Palace, as part of the Queen's Platinum Jubilee celebrations, in London, Britain June 4, 2022.

MAKING HISTORY

The four days of celebrations to mark the monarch's seven decades as queen began on Thursday with a military parade and a Royal Air Force flypast, and a National Service of Thanksgiving on Friday.

Britain's Queen Elizabeth's Platinum Jubilee celebrations in Cardiff
Britain's Prince William and Catherine, Duchess of Cambridge applaud a rehearsal during their visit to the Cardiff Castle with their children Prince George and Princess Charlotte as part of the royal family's tour for Queen Elizabeth's Platinum Jubilee celebrations in Cardiff, Wales, Britain June 4, 2022.

At the concert, Prince William spoke about his family's record on the environment, while Charles also acknowledged his father, Prince Philip, who died last year aged 99.

"My papa would have enjoyed the show and joined us wholeheartedly in celebrating all you continue to do for your country and your people," he said.

"You continue to make history."

Elizabeth ascended the throne aged 25 on the death of her father, George VI, in 1952, inheriting dominion over a Britain still emerging from the ravages of World War Two and with Winston Churchill as prime minister.

In total, there have been 14 prime ministers and 14 U.S. presidents during her reign; the Berlin Wall rose and fell; Britain joined and left the European Union; and her nation's own once-mighty empire disintegrated, replaced by a Commonwealth of 54 nations. Elizabeth was instrumental in creating the latter and many regard its success as her greatest achievement.

Derby Festival
Horse Racing - Derby Festival - Epsom Downs Racecourse, Epsom, Britain - June 4, 2022 Britain's Princess Anne is seen during the races

Polls suggest a comfortable majority believe the monarchy should remain. A recent Ipsos survey put support for the queen at 9 out of 10 respondents. But Charles is less popular and support among the young is waning.

Supporters see the queen as a source of soft power in the world and a stabilising factor: a bridge between the nation's past and its present.

As Charles delivered his tribute, projections of the queen, which he had selected, were beamed onto the walls of the palace.

These included a carriage ride with former South African President Nelson Mandela during his 1996 state visit and her famous 2012 handshake with former IRA guerrilla commander Martin McGuinness, who later became the deputy first minister of Northern Ireland.

Sunday will mark the final day of the celebrations, when singer Ed Sheeran will join some 10,000 performers and the armed forces for a parade which will trace a route similar to that taken by the queen on her coronation.