After a lifetime of preparation, Charles takes the throne

Prince Charles has been preparing for the crown his entire life [AP]

Prince Charles has been preparing for the crown his entire life. Now, at age 73, that moment has finally arrived.

Charles, the oldest person to ever assume the British throne, became King Charles III on Thursday following the death of his mother, Queen Elizabeth II.

After an apprenticeship that began as a child, Charles embodies the modernization of the British monarchy. He was the first heir not educated at home, the first to earn a university degree and the first to grow up in the ever-intensifying glare of the media as deference to royalty faded.

He also alienated many with his messy divorce from the much-loved Princess Diana, and by straining the rules that prohibit royals from intervening in public affairs, wading into debates on issues such as environmental protection and architectural preservation,

"He now finds himself in, if you like, the autumn of his life, having to think carefully about how he projects his image as a public figure," said historian Ed Owens. "He's nowhere near as popular as his mother."

Charles must figure out how to generate the "public support, a sense of endearment" that characterized the relationship Elizabeth had with the British public, Owens said.

In other words, will Charles be as loved by his subjects? It's a question that has overshadowed his entire life.

A shy boy with a domineering father, Charles grew into a sometimes-awkward, understated man who is nevertheless confident in his own opinions. Unlike his mother, who refused to publicly discuss her views, Charles has delivered speeches and written articles on issues close to his heart, such as climate change, green energy and alternative medicine.

His accession to the throne is likely to fuel debate about the future of Britain's largely ceremonial monarchy, seen by some as a symbol of national unity and others as an obsolete vestige of feudal history.

"We know the monarch and certainly the monarch's family - they're not meant to have political voices. They're not meant to have political opinions. And the fact that he's been flexing, if you like, his political muscle is something that he will have to be really careful with ... lest he be seen as unconstitutional," said Owens, who wrote "The Family Firm: Monarchy, Mass Media and the British Public, 1932-53."

Charles, who will be the head of state for the U.K. and 14 other countries, including Australia, Canada, New Zealand and Papua New Guinea, has defended his actions.

"I always wonder what meddling is, I always thought it was motivating," he said in "Prince, Son and Heir: Charles at 70," a 2018 documentary. "I've always been intrigued if it's meddling to worry about the inner cities, as I did 40 years ago and what was happening or not happening there, the conditions in which people were living. If that's meddling, I'm very proud of it."

In the same interview, however, Charles acknowledged that as king, he wouldn't be able to speak out or interfere in politics because the role of sovereign is different from being the Prince of Wales.

Charles has said he intends to reduce the number of working royals, cut expenses and better represent modern Britain.