Queen Elizabeth II appeared on Buckingham Palace's balcony to huge cheers from crowds of people packed below on Sunday, as four days of celebrations for her historic Platinum Jubilee ended.

Flanked by her immediate heirs, princes Charles, William and George, it was the 96-year-old monarch's first in-person appearance since Thursday, after she was forced to skip several events since then due to persistent mobility issues.

Using a walking stick for support, and wearing a green outfit with white gloves, she remained on the balcony for the singing of the national anthem, "God Save The Queen", waving to the crowds before and after to sustained cheering from those below.

The country's longest-reigning monarch made two public appearances on the balcony on the first day of celebrations Thursday, but that left her in "some discomfort", the palace said, amid her increasing difficulties walking and standing.

She withdrew from a Friday thanksgiving church service and missed Saturday's flat-racing showcase The Derby for only the fourth time since 1952.

She also skipped Saturday night's spectacular "party at the palace" featuring Diana Ross, Andrea Bocelli and Rod Stewart.

Instead, the monarch made a surprise on-screen appearance at the star-studded show in a comedic pre-recorded scene taking tea with Britain's beloved children's book and film character Paddington Bear.

Her public appearance Sunday came moments after British singer-songwriter Ed Sheeran wrapped up a day-long pageant in central London, and the four days of royal festivities, with a rendition of his 2017 hit "Perfect".