Prince William turns 40: Is he getting closer to being Queen Elizabeth II’s successor?

The world watched as Prince William grew from a towheaded schoolboy to a dashing air-sea rescue pilot to a balding father of three.

But as he turns 40 on Tuesday, William is making the biggest change yet: assuming an increasingly central role in the royal family as he prepares for his eventual accession to the throne.

That was clear two weeks ago when William took center stage at the extravaganza concert marking Queen Elizabeth II’s 70 years on the throne, lauding his grandmother as an environmental trailblazer as he delivered a call to action on climate change.”Tonight has been full of such optimism and joy – and there is hope,” he said, as images of wildlife, oceans and jungles were projected on the walls of Buckingham Palace behind him.

“Together, if we harness the very best of humankind, and restore our planet, we will protect it for our children, for our grandchildren and for future generations to come.” Slowed by age and health problems, the 96-year-old queen is gradually handing over more responsibilities to her son and heir, Prince Charles. That in turn gives William, his eldest son, a more important role to play and more opportunities to put the stamp on a new generation of the monarchy.

“William has been very keen to kind of show how he will treat things differently,” said royal expert Pauline Maclaran, author of “Royal Fever: The British Monarchy in Consumer Culture.”

“And so we see that more and more, where the future of the line is being emphasized, with Charles being put more in a kind of holding position for William. We’re always reminded that William is after Charles,” she added.