EXCLUSIVE: Prince William's Succession 'Secret Weapons' Revealed As He Lays Out Blueprint for Radical New Royal Family After King Charles Dies

Princess Eugenie has declared: "Beatrice and I, we've always had each other... she’s my big sissy, she's a legend."

And RadarOnline.com can reveal as the royal family faces seismic generational changes, it's this sisterly bond that is set to be one of future king Prince William's most potent assets.

Princesses Beatrice, 36, and Eugenie, 35 – daughters of shamed Prince Andrew and Sarah, Duchess of York – are increasingly being seen as key figures in the next phase of royal reinvention, palace insiders tell us.

Though currently non-working royals, their growing public presence and unwavering loyalty to the institution have prompted speculation that Prince William, 41, may call upon them for official duties once he becomes King.

Their joint appearance at last month’s Chelsea Flower Show – where they were seen walking arm-in-arm through the gardens – was a visual reminder of their unity.

Eugenie later posted online: "Such a lovely afternoon visiting the @the_rhs Chelsea Flower Show, especially when I get to do it with my sis!"

The siblings’ closeness has become emblematic of a more modern, collaborative monarchy – one experts say William is desperate to nurture given the fractured state of his family, King Charles' cancer and attacks on The Firm by his exiled brother Prince Harry.

Royal commentator Ingrid Seward, 76, editor-in-chief of Majesty Magazine, is among those who believes the sisters' sense of duty, relatability and family-first attitude make them an obvious fit for the future King’s streamlined monarchy.

She said: "When William ascends the throne, Beatrice and Eugenie will be valuable assets, and I'm certain they will get involved with royal duties. It makes perfect sense, because he will need them."

Seward added: "I see them as a sort of double act, working together in the same way as married couples do. Two gorgeous Princesses working together as sisters would be very powerful. I think it would be wonderful, and I think it will happen."

While Beatrice and Eugenie are not full-time working royals, their recent appearances suggest a more formal role may be on the horizon.

In May, Eugenie joined William and his wife Kate at a Buckingham Palace garden party, followed days later by her appointment as a mentor for The King’s Foundation’s 35 Under 35 network.

And Beatrice accompanied King Charles, 76, and Queen Camilla, 77, to an event for the Elephant Family charity, and continues to serve as one of seven Counsellors of State – appointed to step in for the monarch when needed.

Seward added: "I think they would be open to doing more, because they like to give back. They have always been close to William, and the King is very fond of them too."

The York sisters, both young mothers, maintain full-time careers – Beatrice is a vice-president at US tech firm Afiniti, while Eugenie is a director at the international gallery Hauser & Wirth.

They also remain active in charity work, including as patrons of the Teenage Cancer Trust and champions for causes rooted in personal experience – Beatrice with dyslexia awareness and Eugenie with spinal care and anti-slavery campaigns.

A friend of the York family said: "They can't wait to help William reinvent the monarchy for a modern age and come out of the shadows as they both feel they've been sidelined until now.

"They are overjoyed it's 'their time' – and, most importantly, they will do what William says – unlike his brother."

Reader polls consistently place the sisters among the most admired younger royals, with many calling for their return to prominence following the Duke and Duchess of Sussex’s 2020 departure.

Our source added: "They are bubbly and charming – and are all William's got given the state of the royals.

"He certainly can't rely on their dad!"