Fitzwilliams told Express.co.uk: “[King] Charles has impeccable environmental credentials which, in theory anyway, should appeal to younger Britons. He can, however, no longer be an activist.”
He added that pulling in the younger generation was a potentialy “big challenge” for the King.
The royal expert continued: “All polls now show that the monarchy’s appeal to the young is extremely limited.
“It also remains the case that, of the working members of the royal family, only four are under 70.”
READ MORE: The eight bombshell claims Prince Harry made about Royal Family in unearthed interview
Mr Fitzwilliams added: “Queen Camilla is supportive and also her charitable work is impressive.
“The young are unlikely to think of comparisons to Diana, though The Crown, which many watch, is unhelpful in this regard.”
Charles has been a champion for environmental issues throughout a majority of his life.
However, the King – as monarch – has to now observe and maintain political neutrality.
READ MORE: King Charles plans to give sweet gift to Lilibet on her 2nd birthday later this week
Throughout his life, Charles has spent years campaigning for organic farming, conservation and other eco causes.
His past work has led to him being seen as a leading climate advocate – with funding charities and campaigns that have held global significance.
Despite this, his known interest could draw in those – who fall into the younger generation bracket – and could help falling popularity numbers.
Just days before the Coronation – which took place last month – Panorama commissioned a new YouGov opinion poll showed that a majority were in favour of the monarchy.
But there is a sharp contrast in support between different generations – with only 32 percent of 18-24-year-olds in support of the monarchy, compared to 78 percent of over-65s.
