Mr Andersen researched Kate's relationship with her step mother-in-law, as well as the Duchesses' dynamic with Queen Elizabeth II, which led him to sensationally declare that Camilla attempted to instigate a split between William and Kate.
"Camilla is a bit of a snob," Mr Andersen says.
"She's an aristocrat - she has always been moving in royal circles," presumably in reference to her first marriage to Brigadier Andrew Parker-Bowles and her adulterous affair with Prince Charles.
"She had always thought of herself as the heiress to Alice Keppel, her great-grandmother, who was the mistress of King Edward VII."
The Duchess of Cornwall reportedly looked down on Kate, who she saw as a "working-class woman".
"[Kate] is decided from coal miners and her mother was a flight attendant," Mr Andersen notes.
"I was told at the time of Kate and William [short] breakup, and later on as well, that Camilla basically whispered in Charles' ear that it was really time to make - to force - William to make a decision one way or the other."
And it seems other members of the royal family were equally concerned about William and Kate's relationship.
After the Cambridges temporary split in 2007, the Queen's husband Prince Philip reportedly pulled his grandson aside to tell him he "cannot keeping stringing Kate along forever", Express.co.uk reveals.
Queen Elizabeth agreed, telling Prince William a "five-year courtship is long enough".
But William disregarded his reigning grandparents and held out until 2010, when he finally proposed to Kate whilst on holiday in Kenya.
Nearly 10 years later, the Duke and Duchess of Cambridge - future King and Queen consort of England - live between Kensington Palace and Norfolk's Anmer Hall, with their three children Prince George, 5, Princess Charlotte, 4 and one-year-old Prince Louis.