Prince William has spoken about his sadness that his mother is not around to see his children growing up.

Eastern Daily Press: Floral tributes in memory of Princess Diana on the Norwich Gates at Sandringham after her death. Picture: Josh WilliamsFloral tributes in memory of Princess Diana on the Norwich Gates at Sandringham after her death. Picture: Josh Williams (Image: Archant � 2007)

But he revealed that he can now talk about her more openly as the 20th anniversary of her death approaches.

Norfolk-born Princess Diana died on August 31, 1997, after the car she was travelling in was involved in a collision in an underpass in Paris. William was 15 as her sudden death on a Saturday night sent the world into mourning.

Interviewed by Tony Blair's former spin doctor Alastair Campbell for men's glossy GQ magazine, the Prince 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.

Eastern Daily Press: Photo issued by British GQ of the cover of their July issue, which features an interview with the Duke of Cambridge. Picture: Norman Jean Roy/British GQ/PA WirePhoto issued by British GQ of the cover of their July issue, which features an interview with the Duke of Cambridge. Picture: Norman Jean Roy/British GQ/PA Wire

'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.

Eastern Daily Press: Anmer Hall, Anmer. Picture: Ian BurtAnmer Hall, Anmer. Picture: Ian Burt (Image: Archant © 2013)

'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.

Eastern Daily Press: Diana at Sandringham, on Christmas Day, 1988. Picture: Archant libraryDiana at Sandringham, on Christmas Day, 1988. Picture: Archant library

'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.'

George, now three, has spent most of his early childhood at Anmer Hall, on the Queen's Sandringham estate.

The property, which was given to the Cambridges by the monarch, was screened with trees and a drive was re-designed to ensure their privacy.

For much of that time the couple used the hall as their main home, while William worked as a pilot for the East Anglian Air Ambulance, based at Cambridge.

They were frequently seen out and about visiting shops or eating out at village pubs in and around nearby north Norfolk.

Now the couple are making Kensington Palace in London their main home, as they take on more Royal duties.

But they are also expected to visit Norfolk regularly, having grown to love the county during their spell here.

During the interview, the duke also spoke about the aims of the Heads Together campaign he promotes alongside with his wife and younger brother Prince Harry.

He tells Mr Campbell, who is also well known for his campaigning on mental health issues: '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 Thursday, June 1.