The Queen’s “episodic mobility problems” stretch back to last autumn and have led to her cancelling a run of major engagements over the last seven months.
In October 2021, she used a walking stick at a Westminster Abbey service – the first time she had done so at a major event.
A week later, after a busy autumn programme, she was ordered to rest by doctors and advised to cancel a trip to Northern Ireland.
The Queen was secretly admitted to hospital for “preliminary investigations” and had her first overnight stay in hospital for eight years on October 20 2021.
The next day she was back at her desk at Windsor, carrying out light duties.
But concern for her health mounted when she pulled out of more high-profile engagements, including the Cop26 climate change summit and the Festival of Remembrance, with Buckingham Palace saying she had been advised to continue to rest and to not carry out any official visits.
She was intent on attending the Remembrance Sunday service at the Cenotaph, but missed this due to a sprained back.
For more than three months she carried out only light duties, including virtual and face-to-face audiences in the confines of Windsor Castle.
In February 2022 she celebrated her Platinum Jubilee, meeting charity workers at Sandringham House and cutting a Jubilee cake in what was her largest in-person public engagement since October.
Many of her duties are now carried out by video calls, and the country’s longest-reigning sovereign remarked during a in-person audience in February: “Well, as you can see, I can’t move.”
There were fears for her health when she finally caught Covid, testing positive on February 20 2022.
The triple-vaccinated Queen suffered from mild cold-like symptoms, but said the virus left her “very tired and exhausted”.
She carried on with light duties while self isolating at Windsor but cancelled some virtual audiences.
She pulled out the Commonwealth Day service at Westminster Abbey in March, a significant date in the royal calendar given the importance to her of the family of nations, and did not attend the Maundy Thursday service.
But she rallied to honour the Duke of Edinburgh at a memorial service at the end of March, walking slowly and carefully with the aid of a stick, and holding on to the Duke of York’s elbow for support.
With her absence now from the State Opening of Parliament, questions remain over whether the Jubilee Queen will be able to appear during her milestone celebratory weekend – a busy four-day extravaganza with a pop concert, church service, pageant and Trooping the Colour.