When Prince William hosted his inaugural Earthshot Prize awards ceremony this week, nobody would have been prouder than his father Prince Charles.
In fact, speaking before the event, Charles sweetly revealed how proud he was of his eldest son for his work on tackling climate change.
He said: "I am very proud of my son, William, for his growing commitment to the environment and the bold ambition of the Earthshot Prize."
Charles posted his comments to Instagram alongside a touching photo of him and William hugging.
However, it seems the relationship between father and son hasn't always been so smooth. Here we look at their rocky bond...
Early years
William is the firstborn son of Charles and his late ex-wife Princess Diana. They also have a younger son, Harry.
Speaking in 1994, Charles told a documentary, he tried to spend as much time as he could with his young sons.
He said: "William was tiny, I used to muck around with him as much as I possibly could."
However, royal biographer Penny Junor once claimed that Charles had been a "remote figure".
She told the Daily Beast : "It is a slightly tricky relationship because Charles has always been quite a remote figure, he has always been consumed by work.
"That’s not a product of a lack of love. It’s a product of the fact he is so focused on his work, and the need to make a difference in the world that, like many people who are seeking to make a difference in the world, he has sometimes overlooked friends and loved ones beside him.”
Marriage breakdown
As a young boy, William had to witness the breakdown of his parent's marriage that was playing out in the full media spotlight.
At the same time, Charles had rekindled his romance with Camilla Parker Bowles.
And Penny Junor observed, telling Tatler : "Diana shared an awful lot of her misery with William.
"He knew that Camilla was the woman who caused her to be so unhappy – yet equally he knew that Camilla was the woman who made his father happy, so it was extremely difficult for him."
In 1997 - a year after Charles and Diana's divorce was finalised - Diana died following a horrific car crash in Paris, leaving her two sons grief-stricken.
Both William and Harry were staying at Balmoral with Charles at the time, and it was down to their dad to break the terrible news to them.
Growing up
After becoming a single parent, Charles seemed close to William as he entered adulthood and went off to university.
He is believed to have helped William stick out university when he was thinking of quitting and also welcomed the Duchess of Cambridge into the family after they started dating.
And Charles sat proudly at Westminster Abbey in April 2011, when his oldest son and Kate tied the knot.
Living apart
After William married and he and Kate welcomed children, the family settled in Norfolk.
And it was said that William preferred to spend time focusing on his own life than visiting his father four hours away in Highgrove, Gloucestershire.
In 2017, both William and Harry appeared in a documentary to mark the 20th anniversary of the death of Diana, where no mention was made of Charles.
And according to the Daily Mail, Charles was upset by this, with an insider telling royal expert Robert Jobson: "It would have been nice if they had acknowledged his contribution to their upbringing. He was, and tries to be, a jolly good father after all."
Grandfather role
Charles is a grandfather to William's three children - George, Charlotte and Louis.
But in 2015, it was reported by the Daily Mail that Charles had become "increasingly perplexed" about the peripheral role he felt he played in the life of eldest grandson Prince George.
And several years later, William spoke in a documentary to mark his father's 70th birthday, where he revealed his wish for his children to spend more time with their grandad.
He said: “I would like him to have more time with the children… to, you know, play around with the grandchildren.
"When he's there, he's brilliant, but we need him there as much as possible.”
Kate as peacemaker
According to reports, it was William's wife Kate herself who helped to smooth things over between her husband and father-in-law.
And she did this by reportedly helping to organise a family portrait for Charles for his 70th birthday in 2018.
According to the Daily Mail, Kate was instrumental in making the portrait happen, which sees Prince George and Princess Charlotte beaming and cosying up to both Charles and his wife Camilla.
She is also said to have urged Charles to visit their home Amner Hall last summer and took on the logistical challenge of getting her family back home from a holiday on the Isles of Scilly to coincide with his visit.
In doing so, it was reported that the heir to the throne was able to give his grandson George a seventh birthday present in person.
Shared love and bond
Despite their sometimes bumpy relationship, Charles and William are now said to have a bond "built on love, affection and respect".
The pair both share a passion for tackling climate change and recently William paid tribute to this father for his work in this area.
In a foreword for the Earthshot Prize book, William describes Charles, as well as his grandfather Prince Philip, as “pioneers in the environmental movement".
He writes: “Following in their footsteps, I have seen people all over the world face what seem like insurmountable challenges yet come together with collective ambition, and a can-do spirit, to find solutions to them."
Meanwhile, both are given seats at the table now alongside the Queen when it comes to making decisions about the future of the royal family.
A source told Vanity Fair : "They will both be kings one day – and William’s oldest son will be king – and that is something that connects them and has brought them closer in recent years."
