The Royal Family's secret weapon exposed - and it's not Princess Kate

Queen Camilla has been described as the secret weapon within the Royal Family. The 78-year-old has often been seen as a divisive figure among fans, with opinions ranging from intense early scrutiny to a more recent appreciation for her stability in the Firm.

Christopher Wilson, who is the author of A Greater Love – Charles and Camilla, has insisted that she has a secret, steely nature and has earned herself a "ruthless streak". As reported by the Mail, Mr Wilson said: "She's every bit as convincing as the old Queen Mother was when it comes to putting on a sweet smile and saying just the right thing to put people at their ease.

"But – again like the Queen Mum – there's a ruthless streak to Camilla which she takes care to keep hidden from view."

Speaking further of Camilla's role within the monarchy, he added: "Her job, as she sees it, is to support and protect her man. Her predecessor as Queen Consort, Elizabeth, did just the same during the war years and after with her husband, King George VI.

"Monarchy is about survival, and Camilla understands that.

"She's read the history books and knows how, when the House of Windsor was brought to its knees in 1936 with the Abdication of King Edward VIII, she put fire in the belly of her reluctant husband, turning him into a successful wartime monarch who did a great double-act with Prime Minister Winston Churchill.

"King George needed her iron-clad courage, just as King Charles needs Camilla's today."

The Firm's secret weapon has often been Princess Catherine, who also joined the family through marriage.

Christopher Andersen, who is the author of “Kate!,” previously told Fox News Digital that the 44-year-old's modern approach, family values and “soft power” have seen her excel as a true asset.

Duchess Sophie has also been described as an asset to the family due to her work ethic and close bond to future generations.