The 94-year-old is the longest-serving monarch in British history and has served as head of state for 68 years. The Queen’s retirement plans have resurfaced in recent weeks with a number of major milestones on the horizon. Several royal experts have indicated that the Queen may step down from the service after her 95th birthday in 2021 or within 18 months when she celebrates her 70th Platinum Jubilee.

Grant Harold, the former royal butler of the Prince of Wales, believed the Queen would remain an official monarchy until death, but insisted that she could “hand over the reins of kingship in everything but the name” to her son.

Harold, who served in the royal family from 2004 to 2011, added that Charles may inherit more patronage from the Queen in the coming years.

He also noted a promise that then-Princess Elizabeth made on her 21st birthday in 1947.

The future queen pledged to serve her country “throughout her life” during a speech in Cape Town on April 21, 1947.

Talking to Harold said: “I doubt very much that the Queen abdicates because she promised the nation and the Commonwealth in 1947.

“Since they are traditional, I don’t see them breaking that promise.

“It is possible that she may assume more duties, give up sponsorship of charities that still sponsor her, or even enter a semi-retirement phase and hand over the reins of ownership in everything except the name for her son Prince Charles.

“But as far as being ours is ours, I think it won’t change until you die.”

The Queen became the longest-serving monarch in the United Kingdom on 9 September 2015.

She surpassed the record of 63 years, seven months and two days set by Queen Victoria.

The Prince of Wales became the heir at the age of three when his mother, Princess Elizabeth, ascended the throne after the death of her father, King George VI, on February 6, 1952.

His mother’s historical judgment meant that Charles was the longest-serving heir to the throne.

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Earlier this month, the government announced plans to celebrate the Queen’s 70th anniversary as Head of State in 2022.

The minister confirmed that an additional bank holiday will be granted as part of the four-day weekend starting June 2.

Culture Minister Oliver Dowden said the event would be “a truly historic moment, and deserves an unforgettable celebration.”