The Queen is "pacing herself" amid fears that she isn't able to stand for long periods of time.
The Sun reported that senior royal aides at Buckingham Palace are accepting that the "frailties that come with living a long life" are finally catching up with her.
A royal source told the Telegraph, "It's about pacing her diary now.
"She has said herself that she is as committed to service as ever, but that will have to take a slightly different form."
British actor Christopher Biggins claims the Queen has been recently using a wheelchair and is cancelling appearances because she's "proud" and "doesn't want to be seen" struggling to walk.
He told GB News,"It's so very sad and I hope she is able to make her anniversary celebrations.
"I have heard that the reason she's not doing a lot of the events that she should be doing and cancelling them is because she is in a wheelchair."
Another royal expert also claimed that the Queen is finding it "extremely difficult to walk or stand for long periods".
Phil Dampier told the Telegraph, "She will make a huge effort to attend the Prince Philip memorial, but they will have to make allowances for her – and no one will begrudge it.
"She's nearly 96."
It comes after reports military-style plans are being put in place to get the Queen to a memorial service for Prince Philip on March 29.
The Queen pulled out of the Commonwealth Day service last week amid fears for her comfort.
Palace sources said she is suffering mobility issues that leave her struggling to get around, but she is determined to attend her late husband's service at Westminster Abbey.
It's understood senior staff will fly her by helicopter on the 15-minute trip from Windsor Castle to Buckingham Palace.
Her aides do not want her to walk the 100m from the Abbey entrance to get to her seat. Instead, they will drive her the short distance from the Palace and seal off the entrance so they can park in private outside a side door.
A football-style tunnel or six-foot privacy screens could be put up to stop photographers from capturing her as she leaves her car.