William's interview with Eugene Levy is the most open we've ever seen him

Prince William's conversation with Eugene Levy on the actor's Apple TV show is revealing on many levels.

It has clarified his vision for his own reign once he becomes king, reinforced how stressful family life has been for him, and given us a few personal details about him we didn't know before.

Here are our main takeaways from his interview.

This was a different type of royal chat

Traditionally, interviews with the Royal Family come around rarely and when they happen they are formal.

There is usually a room in a palace, set up with cameras and lights. The interviewer will likely be an experienced presenter or journalist. There would have been weeks of briefing notes and discussions about subject areas.

It is a tried and tested formula. But it is now clear this isn't Prince William's way.

Part of his openness here comes from the setting and the context. He is at home at Windsor, he's on familiar territory, he's walking his dog, he's in the pub. William just seems more relaxed in that space, and talks more freely.

The choice of interviewer matters too. He told the actor that he was a fan of his and had loved watching the American Pie films - the coming of age movies starring Levy as a long-suffering father.

There have been some eyebrows raised about revealing so much to a Hollywood actor rather than a more forensic interviewer.

There were no questions on his relationship with his brother, Harry, nothing on his view of Prince Andrew's place in the royal family.

But even with those missing components, we still got something new and interesting.

William didn't falter when asked about his children and about what kind of king he wants to be. He would have probably been more restrained and uptight if it hadn't been Levy asking the questions.

Prince William also revealed he rides an electric scooter around Windsor Castle

William is set on change

It has always been clear that Prince William has his own take on his public role. "A smaller R in royal" is how he previously referred to it.

But the words "change is on my agenda" and not being "suffocated" by history make it very clear that he has a vision for monarchy that will look forward rather than back.

Those who work with the prince and his family are cautious about how those words are interpreted.

One palace staffer told me: "He's not afraid to ask questions about how and why things are done. If the answer is because that's how we've always done it then he just won't accept it."

The Duchy of Cornwall - the financial portfolio that provides an income to the heir to the throne - is cited as an example of William going in and leaving "no stone unturned" in terms of how it is run and what needs changing.

There is new leadership there, a focus on social action and a very involved prince.

One source told me that when he is king, William will be "deep in the roots of the management of Monarchy HQ".

Don't expect the big stuff to change dramatically. There will definitely be a coronation. Trooping the Colour and Remembrance Sunday will remain fixed and important parts of the royal year, and jubilees and big occasions will still be celebrated.

But William as king will have his own way of doing things.

Prince William was asked about his children and about what kind of king he wants to be

He rides an electric scooter at the castle

The programme is filled with small details about the prince – many of which we didn't know before.

He rides an electric scooter around the grounds of Windsor Castle, but still describes himself as "a late person". A favourite drink is a pint of sweet cider.

None of his children currently have their own phone – something he said he and the princess were strict about.

He loved running down the wooden floors of Windsor Castle with his cousins when he was younger trying to avoid getting splinters.

His children now do the same but the floor has been carpeted, so is less perilous. His eldest son, Prince George, now knows more about history than his father.

And he describes his children's favourite activities – it is football and hockey for George, netball for Charlotte, while both Charlotte and Louis like trampolining.

"As far as I can tell they're jumping up and down on the trampoline and beating each other up," says their dad.

Prince Harry gets a brief mention

The prince's younger brother, Harry, gets one fleeting mention in the show. There are no direct questions about him, but William brings him up in a conversation.

"I hope we don't go back to some of the practices in the past that Harry and I grew up in. And I'll do everything I can to make sure we don't regress in that situation."

He was referring to some of the more chaotic aspects of his childhood and how difficult the press attention and intrusion had been.

The sibling relationship still remains deeply fractured following Harry's public criticism of the Royal Family. There are no signs of that changing right now.

Still, it is interesting to hear William just say his brother's name out loud in public.

The strain of Kate's illness is clear

Prince William has mentioned the strain of having both his wife and father unwell a number of times over the past year and a half.

He doesn't shy away from discussing it again here with Levy. William is asked directly about his wife being in remission, about how his children have coped.

He uses the world "overwhelmed" to describe how he has felt at times.

It is just further confirmation of how unsettling the experience has been for him and his family and it has obviously reinforced his desire to put his wife and children first.

"It's just important to be there for each other and to kind of reassure the children that everything is OK," he says.

Prince William has previously spoken about the strain of his wife's illness

The choice of Apple TV is important

The royal media teams are taking a much broader perspective on the type of media work they now do.

A lot of energy is spent on their Instagram posts and YouTube channels. The King is currently working on projects with both Netflix and Amazon.

Apple fits the strategy of engaging a wider number of media platforms and looking for different ways of presenting royalty globally.

It's an approach that isn't without risk for William.

We were told there were no agreed questions or approved areas of discussion and that he was opening up parts of Windsor Castle to the actor and film crew.

But the project has worked for both Apple and Kensington Palace. Apple has a programme making headlines and Kensington Palace feels William has emerged as "a human and easy to relate to guy", according to sources.

This was an unusual place for such an interview

Sometimes royal revelations are found in unexpected places – a prince opening up to one of his favourite actors from his teenage years was a bit of surprise.

But it has shown an heir to the throne managing the stresses of family with his future on his mind.

A royal source summed it up.

"For all too long, we've seen the royals as perfect," they told me. "Here we see William as a human being, in a pub, with a pint, chatting.

"It's the most open we've ever seen him."