Prince Charles like you've never seen him before

Prince Charles, the man who will one day be king. But how much do we really know about him? Photo / Getty Images

There is a side of Prince Charles that few people outside his family and inner-circle have ever seen — until now.

A film crew got unprecedented access to the Prince of Wales over the last year for a special BBC documentary to mark his 70th birthday later this month. Director John Bridcut has worked with Charles and other senior royals before, but he still got an extraordinary insight into the man who will one day be king.

"He's got amazing energy and has so many balls in the air at any one time, it's incredible how he manages that. He works very hard," Bridcut told news.com.au.

The Duchess of Cornwall is a big factor in why Charles is so happy. Photo / Getty Images

He was in no doubt the man the public saw at official engagements was vastly different to the one revealed in the documentary Prince, Son And Heir: Charles At 70.

"When he is not doing an official engagement he is in private meetings and desk work so he is on all of the time. There's the more formal meetings like with military and so on and the occasional politicians and ambassadors, but there are all his charities and organisations he is patron of who do have regular meetings and they send reports and updates."

Charles walked Meghan down the aisle during her May wedding ceremony. Photo / Getty Images

Bridcut was told the Prince would attend 500 meetings a year — but it was what happened behind closed doors that really surprised this experienced royal watcher.

"When I was at Birkhall, his Scottish home near Balmoral, I was amazed when I spoke to one of his staff. She will be at his side when he is up at Scotland largely out of the public eye and there will be a call when the work is piling in and she was on call to go and do office work with him at 10.30pm at night — until midnight — with work carrying on when she got back to her own office."

It was that side of Charles, and the dedication of his staff, that even the strongest royal supporters might not be aware of.

But there were other insights as well, from his wife Camilla, the Duchess of Cornwall and his sons, Princes William and Harry, that should help shape a public who still may not know what makes him tick.

"I don't think he is properly understood. I think there are still people, and they are in declining numbers, who blame him for the divorce and (unhappiness) of Princess Diana. That has really clouded judgment of him and it has also affected perceptions of Camilla, but I think that is changing now."

Prince of Wales "at work" at a reception for Queen Maxima of the Netherlands at Buckingham Palace in London this month. Photo / Getty Images

Bridcut attributed that to Camilla's impressive performance over the past 12 months which is captured on the documentary.

"She's supportive of him and they make an interesting team. She has done quite an eloquent interview (for the doco) where I hope people will get a fresh view of her as well."

Both his sons were interviewed and Bridcut said their pride in their father shone through.

"I think he's very proud of them too and I found in their interviews they were surprisingly passionate about their father's work. It was not dutiful — they really admired him."

Charles as king

Much has been written and speculated about Prince Charles' strong desire to become king. But Bridcut's impression was that he was quite happy with his current role and wasn't longing for it has been so often suggested.

"Becoming king would involve change from what he is doing now. He gets great satisfaction from his work as Prince of Wales so that will be a hardship to step back from that."

What many people forgot was that he had lived with the idea of being king for as long as he could remember. So rather than agitating for something to happen, it would just be a natural progression of his life.

Charles will one day be king - but he's apparently in no hurry. Photo / Getty Images

At 70, Prince Charles is the longest serving heir to the throne.

"He knows it's coming. I don't think he's wanting it, but he is not wanting to avoid it, rather than it's just something that is going to happen."

What is unknown is when it would happen. It could come "suddenly" or happen over a much longer period.

"We don't know what is going to happen with the Queen. He knows it's going to happen it's not though he is itching to be king … to some extent it is a burden, but I don't think he sees it in that sense. It's not something he is dying to do."

Prince Charles will bring a different style to the monarchy than his mother the Queen. Photo / Getty Images

Bridcut thought Charles was the happiest he had ever seen him. That happiness was probably due to Camilla and seeing how happy both his sons were.

"The thing I will take away from this year is if people think, 'What sort of king will he be?' each monarch, like each leader, is different than any other. What people will find really surprising is that while he is good in formal situations, he is quite refreshing in that he can go and joke with people which is not something the Queen does."

Prince Charles will turn 70 on November 14 and the day will be marked by a lavish party held in the State Rooms at Buckingham Palace.