Former British Prime Minister David Cameron held trial audiences with King Charles III

The importance of King Charles should not be underestimated, although in the United Kingdom the monarch is a largely ceremonial former British Prime Minister DavidCameron said Norah O’Donnell, anchor and editor of the CBS Evening News.

The interview comes as King Charles III takes over the throne in the United Kingdom after death of his mother, Queen Elizabeth the second. The Queen’s funeral is set to take place on September 19.

Cameron is one of 15 prime ministers to have held office during her 70-year reign. Just a week ago, Queen Elizabeth performed one of her final acts before her death: she accepted Boris Johnson’s resignation and Invitation of the new Prime Minister Liz Truss to form a government.

Queen Elizabeth had weekly meetings with every prime minister in a so-called “private audience”. Cameron told O’Donnell that during his tenure from 2010 to 2016, he held trial audiences with Charles to prepare him for assuming the crown.

“He knew his mother couldn’t last forever,” Cameron said. “Although for those of us born since 1952, we’ve always had the queen. And it feels like a stone of our lives has disappeared. So, I think he knew that one day he would take the role. He’s thought about it carefully. He wanted to get every part of it right.”

O’Donnell asked what kind of real power the new king could have.

“In our system, the king is now the sovereign, but Parliament is sovereign,” Cameron replied.

“So it’s mostly ceremonial, but we shouldn’t underestimate its importance in two ways,” Cameron continued. “For one thing, I think our system of constitutional monarchy and democracy has brought us great success and stability. The politicians down here can fight it all they want. We have a unifying figure at the top.”

“And the second thing I want to say and feel very deeply after seeing Queen Elizabeth II in action is that she was the greatest civil servant in the world and one of the greatest diplomats in the world,” Cameron added. “Look at what she did to bring Britain and Germany together after the war. Check out what she has done to help the transition to a non-racist South Africa. Look what she did when I was prime minister. Her visit to the Republic of Ireland and healing so many wounds in that regard was remarkable, only she could have done it.”

When Queen Elizabeth ascended the throne, she was the head of state in 32 countries that made up the Commonwealth. Now that has been reduced to 15 countries, for which King Charles serves as head of state, and some have already revived the debate about leaving the Commonwealth.

Cameron said it was “their decision” whether any of those remaining countries wanted to leave. “But I think people can see, and they’re seeing this week, that a constitutional monarchy where your head of state is above politics and is a symbol of unity and a symbol of service and duty, and your politicians those below be able to fight problems. It’s a good system,” he continued. “It has served us well, and it has served others well.”

On a lighter note, Cameron, who has had so many private audiences with Queen Elizabeth, recalled that she had a “very good sense of humor” – and was a “phenomenally good driver”.

Queen Elizabeth II was the longest serving British monarch in history when she died last week at the age of 96. On Monday, Britain’s two chambers of parliament gathered at London’s Westminster Hall to offer their condolences to King Charles and his wife Camilla, the Queen consort.

“Parliament is the living and breathing instrument of our democracy,” the king told the assembled politicians. “At a very young age, Her late Majesty pledged to serve her country and her people and uphold the worthy principles of constitutional government that lie at the heart of our nation. She kept that vow with unsurpassed devotion. She set an example of selfless duty which, with God’s help and your counsel, I am determined to follow faithfully.”

King Charles then flew to Edinburgh to escort his mother’s coffin along with his three siblings, Princess Anne and Princes Andrew and Edward.