The Duke of Cambridge has spoken about his sadness that his mother is not around to see his children growing up.
But he revealed that he can now talk about her more openly as the 20th anniversary of her death approaches.
Interviewed by Tony Blair's former spin doctor Alastair Campbell for GQ magazine, William said: "I am in a better place about it than I have been for a long time, where I can talk about her more openly, talk about her more honestly, and I can remember her better, and publicly talk about her better.
"It has taken me almost 20 years to get to that stage.
"I still find it difficult now because at the time it was so raw.
"And also it is not like most people's grief, because everyone else knows about it, everyone knows the story, everyone knows her.
"It is a different situation for most people who lose someone they love.
"It can be hidden away or they can choose if they want to share their story."
Speaking about his mother not being around today, William said: "I would like to have had her advice.
"I would love her to have met Catherine and to have seen the children grow up.
"It makes me sad that she won't, that they will never know her."
Talking about his wife and children, George, who is four in July, and two-year-old Charlotte, William said: "I could not do my job without the stability of the family. Stability at home is so important to me.
"I want to bring up my children in a happy, stable, secure world and that is so important to both of us as parents.
"I want George to grow up in a real, living environment. I don't want him growing up behind palace walls. He has to be out there.
"The media make it harder but I will fight for them to have a normal life."
The duke also spoke about the aims of the Heads Together campaign he promotes with his wife and brother Harry.
He tells Campbell, who is also well known for his campaigning on mental health: "Smashing the taboo is our biggest aim.
"We cannot go anywhere much until that is done.
"People can't access services till they feel less ashamed, so we must tackle the taboo, the stigma.
"For goodness sake this is the 21st century.
"I've been really shocked how many people live in fear and in silence because of their mental illness.
"I just don't understand it. I know I come across as quite reserved and shy.
"I don't always have my emotions brewing, but behind closed doors I think about the issues, I get very passionate about things.
"I rely on people around me for opinions and I am a great believer in communication on these issues.
"I cannot understand how families, even behind closed doors, still find it so hard to talk about it.
"I am shocked we are so worried about saying anything about the true feelings we have.
"Because mental illness is inside our heads, invisible, it means others tread so carefully, and people don't know what to say, whereas if you have a broken leg in plaster, everyone knows what to say."
The full interview appears in the July 2017 issue of British GQ, which goes on sale on June 1.