Princess Anne, beloved sister of King Charles, is focused on rigorous training of Princess Charlotte.

The Princess Royal wants Prince William and Kate Middleton’s only daughter to become the ‘perfect Princess’ in light of her significant role in the survival of the monarchy.

An insider told Aussie weekly Woman's Day: "Anne's also inadvertently giving her some juicy gossip on the family by going through some of the worst faux pas a royal can make. From her uncle partying in Nazi uniforms to Beatrice's dreadful fascinator at her parents' wedding."

They added: "They're talking all the time about everything and anything. Women’s football, sailing, horses, ballet, fashion, manners... Essentially she's foolproofing Charlotte into becoming the perfect princess and standby queen."

The source then went on to reveal that both Kate and Prince William are happy with Charlotte’s progress under Princess Anne’s supervision.

They noted: "They couldn't imagine a better role model than Anne, who is renowned for her work ethic and impregnable support for the King.

"She doesn't put a foot wrong whilst still having her opinions not only heard but respected. Anne was invaluable to Kate during those early uncertain years, especially as a commoner.

"She wants Charlotte to have the same candid tough love Anne gave her,” added the source.