Queen Elizabeth II becomes UK's first sovereign to celebrate her 90th birthday

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 reaching 90 is a happy achievement for anyone but it's no excuse for slacking off in the view of the duty-conscious queen, who vowed service to her country at age 21 and has never retracted it.

She's been a very strong female influence," Prince William said on Sky News. "And having lost my mother at a young age, it's been particularly important to me that I've had somebody like the Queen to look up to and who's been there and who has understood some of the more, um, complex issues when you lose a loved one."