Britain’s Princess Diana and sons Harry, center, and William at the commemorations of V-J Day in London in 1995. (Johnny Eggitt/Agence France-Presse/Getty Images)

Princes William and Harry are good lads — and either would make a proper 21st-century king. Given all that has happened, that is amazing.

On the 20th anniversary of the death of the People’s Princess, the British people have reached a consensus: Diana raised two relatively normal, capable, flawed but decent, and maybe even exceptional sons, under extraordinary circumstances.

That one of them, Harry, once dressed up as a Nazi is mostly forgotten. That the other, William, is a little dull is okay.

On Wednesday, the eve of the anniversary of Diana’s death, the princes paid tribute to their mother by visiting a memorial garden planted in her honor at Kensington Palace, her former home. Afterward, they stopped to look at the flowers and messages fans started leaving outside of the palace gates this week.

The princes also talked to some of the onlookers who had braved the soggy London weather to pay their respects.

“Harry is really nice — I’m shaking!” said Gracie Oxby, an 8-year-old who had a brief chat with Harry before handing him a bouquet of flowers that the prince laid next to other floral tributes.

All eyes are now on the next generation of royals as the world remembers the strange and unsettling tabloid days surrounding the death of Diana, killed in a horrific car crash in a Paris tunnel on Aug. 31, 1997. 

William was 15 then; Harry was 12. That they were young and that it was heartbreaking escaped no one. Billions watched the televised reports that day, one of the largest global audiences ever assembled.

Prince William, left, and Prince Harry, the sons of Diana, Princess of Wales, bow their heads as their mother’s casket is taken out of Westminster Abbey in London after her funeral. (Adam Butler/Agence France-Presse/Getty Images)

Since then, the pair has done well. To recap, the princes got through their teens and survived their roaring 20s without fatal embarrassments.

There was plenty of partying — and some jousting with paparazzi outside night clubs. But both served honorably in the military, which the British public applauded.

William was a pilot for the East Anglian Air Ambulance until last month. He had a day job. His crew saved lives. 

Harry served as an Apache attack helicopter pilot in Afghanistan. Two tours. He got high marks for trying hard not to draw too much attention to himself. Or as the Sun put it in a tabloid headline, “From wild nights to fire fights: How Prince Harry became a man.” 

Once dubbed the Party Prince, the ginger-haired bachelor Harry has settled down, a bit. He is now dating the American actress Meghan Markle. He understands your interest, but issued a statement through his Kensington Palace spokesman asking people to back off.

These days, William and Harry are busy promoting charities that seek to help disabled veterans and those with AIDS. And, most remarkable, they are speaking out on the stigma surrounding mental-health challenges — by discussing their own, and by extension, very delicately, their mother’s struggles. She suffered from depression and bulimia.

Catherine, Prince William and Prince Harry race during a Marathon Training Day at Queen Elizabeth Olympic Park in London in February. (WPA Pool/Getty Images)

None of this was guaranteed.

That neither prince became a punchline, an afterthought or train wreck — growing up in the selfie age under the all-seeing eye of the most unforgiving tabloid culture on earth — is remarkable.

Their parents, Charles and Diana, had a deeply unhappy public marriage with the most lurid details splashed on the front pages of the world’s newspapers for years. The fascination continues. 

A documentary that aired on Britain’s Channel 4 two weeks ago generated news about how much sex — or not so much — Charles and Diana were having as their marriage cratered, mostly because Charles could not get over his one true love, Camilla Parker Bowles, whom he later married and who is now the Duchess of Cornwall.

Although many might wish otherwise, the 68-year-old Charles will almost certainly be king when his mother, the 91-year-old Queen Elizabeth II, dies.

In Britain, at least now, Charles appears a kind of afterthought, a vintage image. The enduring moment from Diana’s funeral 20 years ago is not of Charles but of sons William and Harry, walking behind their mother’s flag-draped casket, their heads bowed as they shuffled forward between immense ranks of mourners, most silent, but some wailing, others nearly hysterical.

It was a “long and lonely walk,” William says in a new BBC documentary, “Diana, 7 Days,” one of several marking the 20th anniversary of Diana’s death. William said he tried to hide behind his floppy blond bangs, which were like a “safety blanket.” 

Reflecting on the experience today, William says he had many roles to play that day: He was a grieving teenage son, yes, but he was also Prince William, the nation’s future king. 

There was a balance, he said, “between me being Prince William and having to do my bit, versus the private William who just wanted to go into a room and cry, who’d lost his mother.”

British Princes William and Harry appear in a new documentary to honor the anniversary of their mother's death and recount their reactions to her fatal car crash 20 years ago. "I wanted her to be proud of the person I would become," Prince William said.

Until recently, William and Harry have not spoken publicly like this about their mother and what it was like to cope with her loss when they were so young.

It is hard to overstate just how unusual it is, even in 2017, for the queen’s subjects to see the princes on the television talking so openly about Diana. 

Old-school British aristocrats are renowned for the stiff upper lip. The royals can be reserved to the point of hypoxia, in a mostly mute doggedness, viewed charitably as keeping calm and reigning on.

The queen has ruled for more than 65 years, and she has given exactly zero interviews during her long reign.

But William says he felt now was an appropriate time to honor his mother’s memory. In the two documentaries, the princes paint a portrait of a fun-loving, cool mum who is dearly missed. 

The princes light up when they talk about Diana playing pranks — from hiding candies in socks to sending rude cards to her sons at school to arranging supermodels to surprise William at their home. 

“Our mother was a total kid, through and through,” Harry says in the HBO documentary “Diana, Our Mother: Her Life and Legacy.” 

“One of her mottos to me was, ‘You can be as naughty as you want — just don’t get caught.’ ” 

Prince Harry chats to sports stars at a 'Heads Together BBQ' at Kensington Palace regarding challenges they have faced during their lives.

 In 2012, Harry was photographed naked in Las Vegas during a game of strip poker. He didn’t really lose that hand.

 Today, Harry, 32, lives in a cottage on the grounds of Kensington Palace. 

 In his post-army career, Harry founded the Invictus Games, a sporting event for disabled veterans. To help publicize it, he roped in the queen for a promotional video with the Obamas that went viral on Twitter. 

Proving that the royals have a sense of humor.

 His older brother, William, second in line for succession after his father, Charles, is the less-interesting one, with the thinning hair and the glamorous wife. He doesn’t have the same bad-boy allure as his brother, but he hasn’t fully escaped criticism from the news media. 

 “Work-shy William” is his nickname in some tabloids, upset that he hasn’t clocked up enough royal duty hours. “Throne idle” said one front-page headline in the Sun.

 William defended himself against the gibes, saying that he was concentrating on being a good father, pilot and a royal. But he will soon be clocking up more duties in service of the realm. 

William and Kate, both 35, recently packed up the fam — George, 4 and Charlotte, 2 — and moved their main residence from Anmer Hall in Norfolk, a relatively secluded area in eastern England, to Kensington Palace in the bustling British capital. Prince George starts school this fall in Battersea, south London, a few miles from the family home. 

 Both William and Harry are now full-time royals, and as such carry out “engagements” — as they are called — on behalf of the queen, and draw attention to various charities. 

Prince William and Prince Harry arrive for the marriage of Pippa Middleton to James Matthews at St. Mark’s Church in Englefield Green, England, in May. (WPA Pool/Getty Images)

The queen — “the boss” as William has called her — is still very much at the helm, but as she gradually scales back her duties, the younger generation is taking on a greater role. 

Commentators say that William may start to fill in some of the gaps left by his grandfather, Prince Philip, who recently hung up his royal cleats at age 96. 

“In the closing years of her life, the queen and William will make a natural couple,” carrying out royal duties, said Robert Lacey, a royal biographer. He noted that the two have a similar style — reserved, cautious, calm — that contrasts with the more opinionated Prince Charles, the queen’s eldest son and first in line to the throne. In an interview with the BBC, William suggested that he is more likely to rule in a manner similar to the queen’s. 

Some traditionalists have sniffed at the princes’ openness. The queen doesn’t do touchy-feely, and the heirs should follow suit, they say. 

“Time for William to put a royal sock in it and follow his grandmother’s rule of never complain and never explain,” ran one headline in the Daily Mail. 

In a recent poll, 78 percent of those surveyed said William had made a positive contribution to the royal family; Harry, 77 percent; Kate, 73 percent; Charles, 36 percent; and Camilla, 18 percent. 

 “I think they have a difficult job,” said Robert Jobson, a longtime royal correspondent and co-author of “Diana: A Closely Guarded Secret.” “They have to bridge that gap between their mother, who showed she cared about something other than the institution, and also show respect for the monarchy itself.” 

Prince William, Catherine and Prince Harry cheer on runners as they signal the start of the 2017 Virgin Money London Marathon in April. (Chris Jackson/Getty Images)

 Despite their recent openness, it’s widely reported that the princes loathe the media, and William in particular comes across as guarded.

“William has to be more private. He’s the father of two young children, and he doesn’t want a repetition of the abhorrent behavior of the media that chased his mother to her death,” Jobson said.

 In the BBC documentary, William said that when he saw his mother crying, it was usually to do with something connected to the media. He said that this took a toll on him and that he found it difficult as a young boy who wanted to protect his mother from the paparazzi.

 “And I mean a pack, like a pack of dogs, followed her, chased her, harassed her, called her names, spat at her, tried to get a reaction to get that photograph of her lashing out, get her upset,” William said. 

 Last year, Harry fired his own salvo at the news media, condemning what he said was the media’s  racist and sexist abuse of his girlfriend Meghan Markle, an American actress of mixed race who is arguably best known for her role in the TV drama “Suits.” The princes have signaled they won’t be talking about Diana as much in the future, but don’t expect them to stop talking about the importance of expressing feelings. 

  “There may be a time and a place for the ‘stiff upper lip,’­ ” William has said. “But not at the expense of your health.”