The Duchess of Cambridge has praised Prince Harry for opening up and talking about the issues he faced after his mother's death describing him as "brilliant".
Kate paid tribute to Harry who revealed in an interview with the Daily Telegraph he spent nearly 20 years "not thinking'' about Diana, Princess of Wales' death and eventually got help after two years of "total chaos''.
The Duchess's words of praise came when she invited a group of London Marathon runners, supporting William, Kate and Harry's Heads Together mental health campaign, to the grounds of her Kensington Palace home to wish them luck.
MORE: Prince Harry praised after revealing long fight to process grief over mother's death
Primary school headteacher Jamie Maloy brought up the subject of Harry's personal confession, telling his royal host: "What I love is your brother-in-law talking the other day, because it just ignited it.
"Everyone's talking about mental health now because someone who is so famous and so much in the public eye has actually turned around and said something hit me hard - the death of a close loved one.
"And I think people have gone 'good on you, because you could have never mentioned that'."
In response Kate, who was casually dressed in black skinny jeans and a stripy top, said: "We all felt there was very much a campaign to get everyone talking and have these conversations, (so) we've got to do the same, you know, do the same - so he's been brilliant."
Mr Maloy runs Viking Primary School in Northolt, north-west London which is supported by Heads Together charity partner Place2Be, a leading national children's mental health organisation.
He added that the prince was a "real hero to a lot of people" and Kate agreed saying "absolutely".
William, Kate and Harry's Heads Together initiative has been running for about a year and has been encouraging the public to come forward and speak about their mental health issues or be a sympathetic ear for someone in need.
The royal trio have been intensifying their campaign in the run-up to the London Marathon, which has made their campaign its official charity, and are hoping the thousands of runners who will be pounding the streets of London on Sunday will be wearing their blue Heads Together headbands.
Earlier Harry handed out headbands when he officially opened the marathon's expo in London's Docklands where runners taking on the 26-mile challenge collected their registration packs.
And in the grounds of the palace Kate put a headband around a Royal Mail post box - with many more due to adorn boxes along the route of the course.
During the event Kate had a heart-to-heart chat about the pressures of motherhood with a Kiss FM DJ who has filmed a video talking about post-natal depression.
The Duchess heard how broadcaster Neev Spencer suffered low periods when she doubted her ability as a mother after her much-longed-for daughter was born last year.
Spencer, who has recorded a Heads Together video chatting with her best friend about post-natal depression, told Kate: "I feel now everyone will see it as something so normal, even for me it kind of nearly went to a really, really dark place, but I managed to scoop myself out."
She said her best friend, who lives in Australia, was the person she turned to for help, with the time difference meaning she was around to offer a sympathetic ear when she had dark periods in the evening.
They also talked about the problems of presenting the "perfect" family image on social media.
The DJ said: "The scary thing about social media sometimes is you put more pressure (on yourself) because you're trying to be this perfect person, and they all look so beautiful and out of a magazine."
Kate agreed with a laugh, saying: "Perfect images of your children, looking perfectly behaved."
But the Duchess had parting words of comfort for the broadcaster, who did not bring her nine-month-old daughter Genevieve to the event as she was teething.
Kate told her "It gets even better and better as they get older, you've got a fun and happy journey ahead of you."