Much has changed at every turn within the royal family, but one aspect has changed little, according to a prominent royal expert.

According to royal historian Robert Lacey, His Majesty is not stepping down from the throne any time soon, despite physical mobility issues, nor has he lost control of anything in the royal court.

"My sense from everyone I talk to is that the queen is in complete control of her abilities and everything in the palace," he told PEOPLE via OK!

It was noted that Her Majesty was absent from the May 10 opening of Parliament and was replaced by Prince Charles and Prince William. Lacey sees their substitute attendance as a significant moment and a major backing for the queen, along with a well-considered decision by her daughter-in-law, Camilla, to one day become queen.

"The Queen is clearly thinking about the future, which can be seen alongside the moment when Camilla said it was her wish to be known as Queen Consort. She asked her sons Charles and William to attend, obviously for the sake of succession and to emphasize partnership and teamwork." Charles is acting on behalf of the Queen, which he has done for some time, and William and Kate are also beginning some of the duties they have performed."

This week, for example, Prince William attended a state funeral in the United Arab Emirates on behalf of the Queen, and Kate Middleton attended a garden party on behalf of Her Majesty. After a string of health problems that began last year, the Queen's attendance at recent royal events has been completely dependent on her physical condition on the day of the event, and "it must be assumed that the Queen will not attend the event," a source told the Mail on Sunday. If Her Majesty the Queen does attend, it will be decided on the day and she will be accompanied by other members of the Royal Family."

But don't be fooled by the fact that her physical mobility may at times hamper her.