Prince William will be a “very radical monarch” when he becomes king, according to a royal expert.

Roya Nikkhah says “the monarchy will look very different quite quickly” – marking a huge difference from the days of his grandmother Queen Elizabeth II.

Nikkhah is the only journalist to have interviewed Kate Middleton’s husband since the queen died, demonstrating her inside expertise.

Speaking on Hello!’s acclaimed A Right Royal Podcast, Nikkhah alluded to two key things that will immediately set the tone for Will’s radical rule.

Firstly, William’s passion to slow down man-made climate change will take a step up from even his father Charles’s enthusiasm.

William’s Earthshot prize encourages people to submit their “innovative solutions to the greatest environmental challenges”.

Prince William said: “The Earth is at a tipping point. We face a stark choice: either we continue as we are and irreparably damage our planet, or we remember our unique power as humans and our continual ability to lead, innovate and problem-solve.

“People can achieve great things. The next ten years present us with one of our greatest tests – a decade of action to repair the earth.”

Scientists have warned of various impacts of environmental challenges – the most serious being food and water shortages leading to the starvation of billions, causing potential mass migration and subsequent wars. Flood threats to major cities will also need to be addressed.

Nevertheless, Wills has been accused of eco-hypocrisy due to his charity’s fossil fuel links, as well as his tendency for private jet trips.

Meanwhile, the second of Prince William’s radical changes will be his coronation – Nikkhah said it will be very different to his father’s, although further detail has not yet been released.

One thing that is not going to be radicalised is William’s title when he becomes King. Nikkhah explained that he liked being referred to as just Prince William for publicity reasons – and will therefore be known simply as King William V.

She said: “When he launched Earthshot he was the Duke of Cambridge, but he called himself Prince William.

“And that’s because he’s keen to be known as Prince William, because the Americans know and love him as Prince William, they love him above all other public figures, according to a recent poll.”