Sarah Ferguson follows Justin Bieber on Instagram.

Sarah Ferguson

Sarah Ferguson

The Duchess of York - who was previously married to Queen Elizabeth's son Prince Andrew - signed up to the social networking site recently and quickly followed a number of celebrities including Justin, 21.

Other stars to get the seal of approval from Sarah, 56, include Justin's ex-girlfriend Selena Gomez, Cara and Poppy Delevingne, Taylor Swift, David and Victoria Beckham, Beyonce Knowles, Elton John and Catherine Zeta-Jones.

Perhaps Sarah was introduced to Bieber's music by her daughters Princess Beatrice and Princess Eugenie as Andrew revealed last year that Eugenie was responsible for his newfound love of will.i.am's music.

He said: "He's now on my playlist, mostly because my youngest daughter put him on. He's a major inspiration to a lot of young people from all sorts of backgrounds - not just because he's famous but he actually has something many others don't have, which is that he cares about giving back to his community.

"I have seen him do it - and it only takes about a sentence from him to change somebody's life.

"I have a very eclectic listening habit. I have classical and, as it were, more modern music. I listen to it sometimes in the car, though mostly when I'm exercising."