The Queen seemed to get along with Meghan Markle right from the start, but a royal biographer claims it was different with Kate.
Author Katie Nicholl claims the Queen "disapproved" of Kate before she married Prince William because of her "frivolous displays of wealth".
Nicholl says in her 2010 biography titled "William and Harry," that the Queen found Kate's extravagant lifestyle she led in London, "unpalatable".
The royals expert wrote: "If [Kate] was not with William at Balmoral then the couple were skiing or holidaying on Mustique.
"Kate was there so often the press dubbed her 'Queen of Mustique', a title that had previously belonged to Princess Margaret."
Reported by The Sun, a source shared with Nicholl: "Swanning from one five-star holiday resort to another is not the prerequisite for a young woman possibly destined to be Queen."
The Queen was uncomfortable with Kate's lavish way of living - glamorous holidays and her social standing in the London club scene.
The author said in the biography: "Britain was now in recession and such frivolous displays of wealth were unpalatable to The Queen."
Middleton was hurt by the Queen's opinion and ignored advice from Clarence House to not make a public statement.
She spoke out claiming she was a photographer, working for her parent's company.
Soon after, an image of Middleton showed up on the website but didn't stay up for long.
Nicholl explained: "It was deemed a step too far and within weeks it had been removed."
Chiming into Middleton's life with critical thoughts, the Queen guided Middleton to more appropriate roles.
Nicholl writes: "The Queen had quietly suggested that Kate affiliate herself with a charity and, by September, she was involved with Starlight, which works with seriously and terminally ill children."
Prince William and Kate Middleton met in 2001 and are assumed to have started dating in 2003.
They briefly split in 2007, but then got engaged in 2010, and married a year later.