Queen Elizabeth II and her husband Prince Philip, Duke of Edinburgh, at the Great Wall during the state visit, in October 1986. [Photo/CFP]

On her actual birthday, the queen generally demonstrates her commitment to duty with a routine engagement in Windsor. The official birthday is always marked with a traditional parade known as Trooping the Colour.

The celebration will end with a huge street party on June 12 at which 10,000 guests will enjoy a picnic and performances.

People are fascinated by the queen's longevity as the UK celebrates the 90th birthday of its monarch, whose reign of more than six decades has overtaken that of her great-great-grandmother Queen Victoria.

She has had 12 prime ministers, from wartime leader Sir Winston Churchill to the incumbent, David Cameron.

"I think the interesting thing about the royal family and in particular about the queen is primarily longevity, a prime Chinese value," said Martin Palmer, 62, Prince Philip's spiritual adviser on the environment.

The queen and her husband have both shown enormous interest in Chinese religion, especially Taoism, according to Palmer, who has worked with the Taoists of China for more than 20 years.

Contact the writers at fujing@chinadaily.com.cn and wangmingjie@mail.chinadailyuk.com

President Xi Jinping with Queen Elizabeth II at a state banquet at Buckingham Palace, London, during the first day of his state visit to Britain, on Oct 20, 2015. [Photo/Agencies]