Princess Diana's astrologer predicts Prince William and Duchess Catherine's compatibility

Princess Diana's astrologer, Debbie Frank, has analysed the The Duke and Duchess of Cambridge's compatibility as they prepare to mark their ninth wedding anniversary in a months time.

• The royal astrologer says Prince William and Duchess Catherine have a 'shared destiny'
• The couple tied the knot in April 2011 - ten years after meeting at St Andrew's University
• They have three children together
• It follows royal news that a file containing information about Princess Diana's death could be kept secret until 2082

A royal astrologer has suggested the Duke and Duchess of Cambridge's relationship is founded on their ability to feel "at home" with each other - a unique quality which is essential for creating a "solid base" and a "family unit".

Debbie Frank - who previously worked with the late Princess Diana before her tragic death in 1997 - has read Catherine and Will's birth chart in order to analyse their compatibility.

She told Hello, "Kate's Moon is in Cancer and to have a partner with the Sun in your Moon sign is the top traditional compatibility criteria. It means you feel at home with each other and have the potential to create a solid base and family unit."

As well as their more "traditional" compatibility, Debbie explains that their birth signs mean their initial spark would have felt "magnetic" and "powerful" during their time at St Andrew's University.

"Kate, a grounded Capricorn, is the opposite sun sign to William's Cancer sun. Opposite signs are magnetically attracted," she explained.

"Capricorn is an anchor for the emotional sensitivity of Cancer and Cancer instinctively knows how to open up the somewhat inhibited goat. Kate and Wills must have experienced that initial love dart as a hugely powerful attraction from the very start."

Thankfully, given their role as patronages for various charities, Catherine and William share a mutual desire to make a difference.

Debbie adds, "Kate is born on a Full Moon, William on a New Moon – so they are both able to connect with the public and both have strong feelings of a special destiny and the desire to make a difference to the world."

But their romance has far succeeded just an initial spark and the Duke and Duchess of Cambridge are now parents to three children - Prince George, six, Princess Charlotte, four, and one-year-old Prince Louis.

And Debbie can see it being a long-lasting and happy marriage as they work towards a shared "mission" in life: "These factors create a unified force around Kate and William, enough differences to keep things interesting and enough shared values to build something long-lasting.

"This marriage is not just about them as a couple but is rubber-stamped as having a powerful mission."