Inside Queen Elizabeth's Decision to Step Back from Jubilee Events: 'She Would Not Want to Stumble'

Queen Elizabeth II Jubilee then and now
Queen Elizabeth II Jubilee then and now

Chris Jackson/Getty Queen Elizabeth

Queen Elizabeth's recent mobility issues limited her to appearances at just a few events over her four-day Platinum Jubilee celebration.

After appearing on the Buckingham Palace balcony for Trooping the Colour on Thursday, the palace announced that the monarch, 96, would not attend Friday's service of thanksgiving in her honor. She lit the Platinum Jubilee beacons on Thursday night, then did not step out in person again until the grand finale on Sunday, when she ended the Platinum Jubilee Pageant with a surprise appearance alongside her family on the palace balcony again.

"The Queen greatly enjoyed today's Birthday Parade and Flypast but did experience some discomfort," a spokesperson for Buckingham Palace said on Thursday.

Her own high expectations for herself are a factor in keeping the Queen from taking part, says royal historian Robert Lacey in this week's issue of PEOPLE: "She would not want to stumble — not for her own sake but for the distress it would cause other people."

RELATED: Kate Middleton Gives Rare Update on Queen Elizabeth After She Skipped Church Service Due to 'Discomfort'

LONDON, ENGLAND - JUNE 05: Prince Charles, Prince of Wales, Queen Elizabeth II, Prince George of Cambridge stand on the balcony during the Platinum Pageant on June 05, 2022 in London, England. The Platinum Jubilee of Elizabeth II is being celebrated from June 2 to June 5, 2022, in the UK and Commonwealth to mark the 70th anniversary of the accession of Queen Elizabeth II on 6 February 1952. (Photo by Chris Jackson - WPA Pool/Getty Images)

Chris Jackson - WPA Pool/Getty Prince Charles, Queen Elizabeth and Prince George

A source told PEOPLE that the Queen's episodic mobility issues flared during the course of the day on Thursday. She was pictured using her cane on the palace balcony as she took the salute and viewed the flypast alongside members of the royal family.

Kate Middleton gave a health update on the Queen on Friday. During a reception held at Guildhall by the former Lord Mayor, the Duchess of Cambridge, 40, told an attendee that the Queen was "fine" after a long day of Trooping the Colour.

"Yes, she [the Queen] was fine, it was just very tiring yesterday," Kate said, according to PA, adding that the monarch "had had a lovely, lovely time."

Prince Charles, Prince of Wales, Queen Elizabeth II, Prince Louis of Cambridge, Catherine, Duchess of Cambridge, Princess Charlotte of Cambridge, Prince George of Cambridge and Prince William, Duke of Cambridge
Prince Charles, Prince of Wales, Queen Elizabeth II, Prince Louis of Cambridge, Catherine, Duchess of Cambridge, Princess Charlotte of Cambridge, Prince George of Cambridge and Prince William, Duke of Cambridge

Max Mumby/Indigo/Getty Prince Charles, Queen Elizabeth, Kate Middleton, Prince William, Prince Louis, Princess Charlotte and Prince George

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The Queen has been experiencing mobility issues in recent months and finds it difficult to stand for long periods. She has been using a walking cane and even complained about mobility problems, joking during an in-person meeting: "Well, as you can see, I can't move!"

Although the monarch appeared on the palace balcony for Trooping the Colour, she didn't take part in the main parade for the first time.

Bill Mott, a former Garrison Sergeant Major of London District who ran Trooping Colour for the Golden and Diamond Jubilees, tells PEOPLE: "In all the years I did the Queen's Birthday Parade, it was Her Majesty the Queen there. To not have Her Majesty arriving was poignant and the fact that she went out onto the balcony was lovely."

"I thought in my heart, how many more times am I going to see her Majesty like that? It was quite sad for a lot of reasons. I know the Platinum Jubilee is meant to be a wonderful occasion and something to mark 70 years, but it was tinged with sadness for me," continues Mott, who is Commandant of Cadets at Valley Forge Military Academy. "It's the end of a very powerful era. How much longer are we going to be blessed with her?"

Queen Elizabeth II and Prince Edward, Duke of Kent on the balcony of Buckingham Palace during the Trooping the Colour parade
Queen Elizabeth II and Prince Edward, Duke of Kent on the balcony of Buckingham Palace during the Trooping the Colour parade

Chris Jackson/Getty Images Queen Elizabeth and the Duke of Kent

In a statement released on Sunday following the weekend's events, the Queen acknowledged her absence.

"While I may not have attended every event in person, my heart has been with you all; and I remain committed to serving you to the best of my ability, supported by my family," she said.