Queen Elizabeth greeted thousands of well-wishers from across Britain and beyond as she celebrated her 90th birthday, demonstrating the world’s oldest monarch’s intent to keep doing the job she has performed for more than six decades.

Usually the Queen’s birthday passes with little ceremony but to mark Thursday’s milestone a beaming Elizabeth, attired in a light green outfit, mingled with crowds during a lengthy walkabout near her Windsor Castle home, west of London.

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Greeting the crowd, the monarch accepted bunches of flowers from children and passed them along to her personal minders – thanking people as she went.

In a rare move in recent years, she then drove through Windsor in an open-topped car with Prince Philip, her husband of 68 years, by her side.

In 2015, Queen Elizabeth surpassed her great-great-Grandmother, Queen Victoria as Britain’s longest-serving Monarch. Despite decreasing her number of her yearly engagements, she has not shown significant signs of slowing down.

The Queen lit the first of 900 beacons to be lit around the UK, including one by her son, Prince Charles at Windsor Castle.

“I send my best wishes to those who are celebrating their 90th birthday … on this shared occasion, I send my warm congratulations to you,” said a post on the queen’s Twitter account.

Close aides say Elizabeth, who has been on the throne for 64 years and is by far the oldest monarch in British history, was far more interested in events to mark her 90th birthday than she had been about overtaking her great-great-grandmother Queen Victoria last September as Britain’s longest-reigning sovereign.

Born on April 21, 1926, Elizabeth shows no signs of retiring let alone abdicating.

A poll last week found 70 per cent wanted her to stay queen compared to 21 per cent who thought she should abdicate or retire.

Speaking to the crowd, Prince Charles was sentimental about his long-serving mother, addressing her a “Mummy”.

“I find it very hard to believe that you’ve reached your 90th year and I suddenly realised the other day that I have known you since you were 22 years old,” he said.

The Queen also opened a new ‘Queen’s Walk’ in commemoration of the moment she overtook Queen Victoria as the longest-serving monarch.

“I send my best wishes to those who are celebrating their 90th birthday…on this shared occasion, I send my warm congratulations to you”

— BritishMonarchy (@BritishMonarchy) April 21, 2016