Prince Charles talks about his future role in the BBC's new documentary

The Prince of Wales was chosen in April by the 53 Commonwealth countries to become the future president. Although the post is not hereditary, her mother, Queen Elizabeth II, who has headed the Commonwealth since 1952, declared that her "sincere" wish was that he would run this country "someday".

But his passion for change has also sparked controversy. Charles would have written to ministers – and even to the prime minister – on topics that were important to him, raising the concern of those who felt that the royal family should not be involved in such debates and feared that he would not be involved in such debates. Once king, he does not stay above politics. in the manner of Queen Elizabeth.

"You know I've tried to make sure that everything I did was political without a party, but I think it's essential to remember that it's n & # 039; There's only room for one sovereign at a time, not two, so you can not be the same sovereign if you're the Prince of Wales or the heir, "said Charles, who will be 70 years old on November 14th.

"But the idea that I will continue to follow exactly the same path if I have to succeed is totally absurd because the two … the two situations are completely different.You only have to watch Shakespeare's plays, "Henry V" or "#"; Henry IV, parts 1 and 2, to see the change that can take place – because if you become sovereign, you play the role in the expected way, "he said.

"So, clearly … I will not be able to do the same things that I did to you as an heir, so of course you operate in … constitutional parameters." But it's a different function . "

A royal source told CNN that the prince would like to state once and for all that he did not plan to be a mediocre monarch, adding that he considered this role as distinct from the one he is in now.

Speaking during his intense campaign on climate change and other issues at "ruffled feathers", the Prince of Wales said he was lucky to be able to count on favorable government personalities who encouraged him to lead a battle of conscience, as former Prime Minister Jim Callaghan and Sir Alec Douglas-Home when he was Foreign Secretary.

Charles added that he thought the public expected him to contribute positively to civil society, given his position.

"So, as you would imagine, I was very encouraged to take an interest in. I think people would already get fed up with it if I did not do it, I would have thought, "he said.

"Prince, Son And Heir: Charles At 70" will be broadcast on the British channel BBC One at 21h. local time Thursday.