The Duke of Cambridge and Prince Harry have a close bond.

Their shared memories of childhood and the support they offer each other has been invaluable in adulthood.

Growing up together, they jointly experienced the scrutiny that comes with royal life.

Prince William, nine, and his younger brother Prince Harry, seven, wave to photographers as they board the Royal Yacht Britannia (Martin Keene/PA)
Prince William, nine, and his younger brother, Prince Harry, seven, wave to photographers as they board the Royal Yacht Britannia (Martin Keene/PA)

Both have served in the military, facing the rigours of training at Sandhurst, followed by a career, for a time, in the forces.

They play polo together, and live close to one another at Kensington Palace, where they grew up.

 Prince William and Prince Harry at Sandhurst Royal Military Academy's Sovereign’s Parade in 2006 (PA)
Prince William and Prince Harry at Sandhurst Royal Military Academy’s Sovereign’s Parade in 2006 (PA)

It comes as no surprise that Harry has asked William to be his best man.

Although different in character, the pair have remained friends, and are at ease in one another’s company, frequently making jokes about each other’s hair at royal appearances.

Harry, more open and outspoken, has always been seen as more of the party prince compared with William.

Considered more reckless and the daredevil one, Harry’s most famous stunts have included being photographed playing strip billiards while on holiday in Las Vegas.

Prince Harry and Prince William pose with a rock python during a visit to the Mokolodi Nature Reserve in Gabarone, Botswana (Anthony Devlin/PA)
Princes Harry and William pose with a rock python during a visit to the Mokolodi Nature Reserve in Gabarone, Botswana (Anthony Devlin/PA)

Future king William is seen as more cautious, and more measured in his approach.

But Harry, who was the spare to the heir until William had children, has settled down in recent years, concentrating on his charity work, and is now preparing to wed American former actress Meghan Markle.

The brothers jointly work together on their Royal Foundation, striving to raise awareness surrounding mental health issues, along with other charitable work.

William, Kate and Harry supporting their Heads Together mental health campaign (Royal Foundation/PA)
William, Kate and Harry supporting their Heads Together mental health campaign (Royal Foundation/PA)

Harry was also William’s best man when he married Kate Middleton in 2011.

Prince William and his bride Kate, followed by best man Prince Harry and maid of honour Pippa Middleton (Kirsty Wigglesworth/PA)
Prince William and his bride Kate Middleton, followed by best man Prince Harry and maid of honour Pippa Middleton (Kirsty Wigglesworth/PA)

At the altar, it was Harry who reassured him that all was going smoothly on the big day, telling William when Kate arrived: “Right, she is here now”.

Harry’s best man speech was said to be both hilarious and touching. William now has to return the favour.

But their friendship has a sadness at its roots.

The brothers had to endure losing their mother at a young age, an experience which brought them together in grief.

The Prince of Wales, Prince William and Prince Harry wait outside Westminster Abbey for Diana, the Princess of Wales’ coffin to enter the Abbey (Adam Butler/PA)
The Prince of Wales, Prince William and Prince Harry wait outside Westminster Abbey for Diana, the Princess of Wales’ coffin to arrive (Adam Butler/PA)

William and Harry were just 15 and 12 when their mother Diana, Princess of Wales, was killed in a car crash in Paris in 1997 and the brothers sought comfort from one another during their difficult teenage years.

The Duke of Edinburgh, Prince William, Earl Spencer, Prince Harry and the Prince of Wales following the coffin of Diana, Princess of Wales (Adam Butler/PA)
The Duke of Edinburgh, Prince William, Earl Spencer, Prince Harry and the Prince of Wales following the coffin of Diana, Princess of Wales (Adam Butler/PA)

Both have spoken of the warmth their mother showed them in childhood and how she strove to make them aware of those less fortunate than them.

The Princess of Wales holding Harry with William (centre) on the balcony of Buckingham Palace (PA)
The Princess of Wales holding Harry with William (centre) on the balcony of Buckingham Palace (PA)
The Prince and Princess of Wales with sons William Harry on cycling trip in Tresco in 1989 (PA)
The Prince and Princess of Wales with sons William Harry on cycling trip in Tresco in 1989 (PA)

Last year, they marked the 20th anniversary of Diana’s death, viewing tributes left for the princess at her former home, Kensington Palace, and commissioning a statue in her memory.

The Duke of Cambridge and Prince Harry after viewing tributes to Diana, Princess of Wales at Kensington Palace ahead of the 20th anniversary of their mother’s death (Kirsty Wigglesworth/PA)
The Duke of Cambridge and Prince Harry after viewing tributes to Diana, Princess of Wales, at Kensington Palace ahead of the 20th anniversary of their mother’s death (Kirsty Wigglesworth/PA)

When Harry turned 21, he described William as the one person on the planet with whom he could talk about everything.

“It’s amazing how close we’ve become,” Harry said. “I mean, ever since our mother died, obviously we were close, but he is the one person on this earth who I can actually really … we can talk about anything.

“We understand each other and we give each other support.”