Queen Elizabeth's son and grandson addressed fans at a concert marking her 70th year on the throne. But Britain's longest-reigning monarch missed the "Party at the Palace."

Queen Elizabeth II was unable to attend the giant pop concert marking her 70 years on the English throne but she electrified the crowd, nonetheless, appearing in a two-and-a-half-minute film alongside Paddington Bear to kick off the celebration.

"While the Queen may not be attending the concert in person, she was very keen that people understood how much it meant to her and that all those watching had a great time," said a Buckingham Palace spokesperson.

The film opened the concert at Britain's Buckingham Palace Saturday evening, part of nationwide celebrations of Queen Elizabeth II's 70 years reign.

The "Party at the Palace" was the main Platinum Jubilee event and came on the third day of celebrations.

Some 22,000 people were estimated to be in attendance at the concert outside the palace.

Prince Charles and Prince William, the queen's son and grandson and next in line for the throne, both spoke at the event to pay tribute to the record-breaking queen.

William, speaking of the future and the environment, said he, like his grandmother, is "an optimist." Charles spoke of his "Mummy" and her service to the nation before urging the crowd to give her a big cheer.

Several musicians performed, including rockers Queen + Adam Lambert, composer Hans Zimmer and Italian singer Andrea Bocelli.

Alicia Keys, Craig David and Eurovision 2022 runner-up Sam Ryder were also on the lineup and performed for the roaring crowd.

A recorded tribute by Elton John was beamed onto the side of the palace as was a message from actress Judy Dench and celebrity soccer player David Beckham, who thanked the queen for her service.

A number of other special guests, including film star Julie Andrews, also offered warm words for the 96-year-old monarch.

The gala event was wrapped up with a performance by Diana Ross.

Queen absent from Jubilee events Friday and Saturday

On the first day of celebrations, Thursday, Queen Elizabeth made two appearances. She waved at crowds from the Buckingham Palace balcony and attended a beacon-lighting ceremony in Windsor.

But she skipped a church service the next day after experiencing "some discomfort," Buckingham Palace said.

The queen did not attend Saturday's Epsom Derby — only the fourth time she has missed the prestigious horse race since 1952.

She is also not expected to attend Saturday's two-and-a-half-hour party in person.

Celebrations stretch to Sunday

Last Thursday and Friday were public holidays in Britain to mark the event, with longer pub opening hours and street parties.

On Sunday, millions of people are expected to share food at "Big Jubilee Lunch" picnics.

The celebrations will close with Ed Sheeran singing his 2017 hit "Perfect" at a pageant in central London.