King Charles hinted at the sort of monarch he wanted to become in unseen footage captured when he was just 18.
The BBC has unveiled archive clips from the Firm's fly on the wall documentary 'Royal Family', which came out in 1969 to provide a more intimate glimpse into royal life.
Footage shows a youthful-looking Prince of Wales talking about his family over clips of him and the late Queen.
He is also filmed decorating a Christmas tree with Princess Anne, building a bonfire at Sandringham and going on an official visit to the Royal Mint with his parents.
At one point, he says: "I like to think of us more as a family rather than as a Firm. I tend to think of my family as very special people.
"And, in that sense, I'm only beginning to see my parents and the rest of my family as other people.
"Do you know what I mean? That you look upon them as having their own different characteristics."
Other intimate family moments include the Queen, Charles and other members of the family taking a trip by hovercraft and the family sitting down to dinner onboard the Royal Yacht Britannia.
At the time of its original release, the documentary made waves as being an unusually rare insight into royal life behind the palace walls, and was watched by 38 million people in the UK when it aired on BBC and ITV.
Queen Elizabeth II later had the programme banned - reportedly in a backtrack on the family's privacy - although this was disputed by royal biographer and Daily Mail columnist Robert Hardman, who insisted this was due to "copyright reasons".
While not officially screened since the 1970s, clips were leaked on YouTube in 2021.
Material archived in the documentary's production however has now come to light in celebration of King Charles' Coronation.
BBC Studios has also been given special permission to use clips from the Royal Family's private home movie footage, showing the King's early love of nature, gardening and animals.
The BBC said the programme is told through the King's own words, as recorded through the decades.
Viewers hear the King discuss his childhood, including his memories of the Queen's coronation, as well as his school days, adolescence, and investiture as Prince of Wales.
It also contains recollections of the King's military service and personal commentary of his commitment to charitable work, as well as his private passions and the role of the institution he now heads up.
Five images from the programme were released last Tuesday, including shots of the then prince flying a plane solo, a visit to the Royal Mint with the Queen, a trip to Malta when he was young, and a shot of the prince decorating a Christmas tree at Windsor.
Simon Young, the BBC's head of history said: "It's a real privilege to be trusted with such rare, unseen archive material to create a new and distinctive portrait of someone so famous and photographed.
"As their majesties' Coronation approaches, this film will give audiences a fresh insight into his remarkable life."
Claire Popplewell, creative director for BBC Studios events productions, added: "This documentary brings audiences a treasure trove of scenes filmed across seven decades in the life of the King.
"Unique and unseen moments with contemporary archive sources and the spoken words of His Majesty, Charles R: The Making of a Monarch tells the story of how a prince became a king."
'Charles R: The Making of a Monarch' was made available yesterday, on BBC One and BBC iPlayer.
