The law was brought in to relinquish powers if a monarch felt unable to carry them out any longer.
It has been predicted the Queen will allow Charles, 70, to be King in all but name when she turns 95.
Her Majesty, now 93, will keep her title, and her husband Prince Philip, 98, will be named Guardian of the Queen.
Royal commentator Robert Jobson previously told the Mail On Sunday he had spoken to a number of high-ranking courtiers who say preparations for the transition of the Crown are gaining pace.
He claims Palace communications staff have been ordered to be “up to speed” on the 1937 Regency Act — the bill that grants power to the heir apparent.
Mr. Jobson said one senior former member of the Royal Household told him: “Out of the profound respect the Queen holds for the institution of monarchy and its stewardship, Her Majesty would want to make sure that she has done everything she can for her country and her people before she hands over.
“Her Majesty is mindful of her age and wants to make sure when the time comes, the transition of the Crown is seamless.”
“I understand the Queen has given the matter considerable thought and believes that, if she is still alive at 95, she will seriously consider passing the reign to Charles.”
Buckingham Palace insiders previously quashed the rumors by saying she is steadfastly committed to fulfilling her duties as British sovereign and referred to the oath she took on her 21st birthday, reported The Sunday Times.
Then heir to the throne, she pledged: “I declare … that my whole life, whether it be long or short, shall be devoted to your service.”