The Queen has returned to public life this week after she was advised not to attend two high-profile engagements.
The 95-year-old monarch's health has been in the spotlight following a missed a trip to Northern Ireland last month, with the palace later revealing she spent a night in hospital.
She was also unable to attend the Remembrance Sunday service - one of the most significant royal events of the year - after spraining her back.
An engagement at the General Synod's inauguration on Tuesday was also planned, but instead her youngest son - the Earl of Wessex - read a statement from her in which she apologised for not attending.
Watch: Prince Charles on Queen's health: 'Once you get to 95, it's not quite as easy as it used to be'
It was the first time the monarch, who is Supreme Governor of the Church, has missed her five-yearly visit to the Synod.
In the speech delivered by Edward, the Queen, who has been under doctors’ orders to rest for nearly a month, said: "It is hard to believe that it is over 50 years since Prince Philip and I attended the very first meeting of the General Synod.
"None of us can slow the passage of time."
The monarch's return to formal engagements began on Wednesday, when she held a face-to-face audience with the outgoing head of the armed forces General Sir Nick Carter
On Thursday, she welcomed the Vietnamese ambassador Nguyen Hoang Long via video link.
She has no major public engagements planned for the rest of the year.
What do we know about the Queen's health?
Senior royals have been keen to downplay any concerns about her health.
Prince Charles batted off rumours during a Royal Tour in Jordan this week, saying: "She's alright thank you very much. Once you get to 95, it's not quite as easy as it used to be."
He added: "It's bad enough at 73," in reference to his own age.
In the latest official update on the Queen, Buckingham Palace said in a statement on Sunday: "The Queen, having sprained her back, has decided this morning with great regret that she will not be able to attend today’s Remembrance Sunday service at the Cenotaph.
"Her Majesty is disappointed that she will miss the service."
Last month, the Palace confirmed that the Queen had spent a night in King Edward VII hospital in central London - her first hospital stay in eight years.
Buckingham Palace said the following day: "Following medical advice to rest for a few days, the Queen attended hospital on Wednesday afternoon for some preliminary investigations, returning to Windsor Castle at lunchtime today and remains in good spirits."
Watch: Prince Charles says Queen Elizabeth is doing 'alright'
But at the time, the Palace was criticised for not announcing the Monarch had been in hospital until after she had left, with some commentators suggesting an absence of communication had allowed rumours to swirl.
While both Prince Charles and Prime Minister Boris Johnson have sought to reassure the public, some have continued to question whether the full details have been shared.
Royal author Ingrid Seward was quoted in the Mirror as saying: "Many will be wondering if we are being told the full story.
"Communications from Buckingham Palace regarding Her Majesty’s recent health have been criticised in recent weeks which will add to the anxiety for many people."
On Wednesday, Buckingham Palace released a photograph of the queen meeting with General Sir Nick Carter, the outgoing chief of the defence staff, in an aim to alleviate concerns.
But BBC Royal Correspondent Nicholas Witchell was quoted as pointing out that while the Queen is standing in the photo, she is not walking.
He said: "Interestingly, perhaps, she is standing as we can see, but we don't see her walking. Now whether there is any significance to read into that I really don't know.
"But there have been suggestions that perhaps one of the problems is a sort of mobility issue."
Which royals will step in?
At the age of 95, it is unsurprising that the Queen will have to do less than previously in terms of Royal duties.
That means other members of the Royal family will inevitably step up to take on more responsibility for official engagements.
They include the Prince Charles and Camilla, the Duke and Duchess of Cambridge, as well as Princess Anne, and Prince Edward and the Countess of Wessex.
The Duke and Duchess of Sussex stepped back from their roles in March 2020 and confirmed earlier this year that they will not return as working royals, while Prince Andrew's working duties have been suspended indefinitely amid the scandal engulfing him around his relationship with Jeffrey Epstein.
Prince Edward standing in for the Queen at the Synod this week is one example of younger royals rallying around the Queen to support her as she becomes less active.
Watch: Queen describes grief and weariness of pandemic in message to General Synod