Her 62 years on the throne still leave her some way short of being the world's longest-reigning current monarch. That distinction goes to Thailand's king, Bhumibol Adulyadej, who will celebrate 69 years on the throne in June. He was just 18 when he became king.
The longest-reigning monarch of all time was Sobhuza II of Swaziland, who was on the throne for 82 years from 1899 to 1982, though the Egyptian pharaoh Pepi II is said to have reigned for up to 94 years, having come to the throne at the age of six. Some historians, however, believe he reigned for 64 years.
If he reigned until he was 100, Pepi II may also have been the oldest monarch in history, though Abdul Momin, Sultan of Brunei until 1885, was either 99 or 100 when he died, the exact date of his birth being unknown.
The Queen is the second-longest reigning monarch in British history, behind her great-great grandmother Queen Victoria, whose record she is due to surpass in September this year.
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