They were clear from the start that their wedding would be about 'real people' rather than diplomats and dignitaries.
And Prince Harry and Meghan Markle couldn't get any more 'real' than Karl Lokko, a former gang leader who has been shot at, stabbed and seen a friend killed – all by the age of 16.
Now a devout Christian who works as a youth community activist, Lokko has forged a remarkable secret friendship with Harry which has seen him secure a coveted invitation to Saturday's wedding, the Daily Mail reports.
More than that, the 27-year-old is now part of the prince's inner circle of friends and trusted advisers, although he is far too discreet to have ever commented on it.
One of the only clues to this under-the-radar friendship was when Harry interviewed Lokko, of South London, as part of his guest editorship of Radio 4's Today programme last year.
A source said: "He may be a boy from Brixton but he has become a really good friend of Harry through their shared passion for youth work and music.
"The prince trusts him implicitly and Karl is now on speed dial on Harry's phone. They regularly text, speak and meet up. Harry thinks he is inspirational."
Lokko grew up on the gang-ridden Myatts Field estate where he saw his first shooting at the age of 12, an experience he describes as "traumatic".
"Four years on, I was heavily involved in gangs," he wrote in The Guardian last month.
"By the age of 16 I had been shot at, cut on the face and stabbed in the chest, and one of my best friends had been killed, just a couple of days before our GCSE exams. I had strayed completely off the path my parents had intended for me.
"Criminal activity was an everyday thing: I would be armed on my way to the local chicken shop with friends. The radical change in my personal identity was alarming even to me. I would sometimes reflect on how far removed I had become from my previous morals."
Lokko is open about the fact that, despite seeing one of his best friends stabbed to death in 2006, he himself became a gang leader who was 'permanently armed', first with knives, then guns.
He headed a 40-strong crew who called themselves MAD – 'Mayhem And Disaster'.
He has said: "I believed it was kill or be killed, I believed drug-dealing was an acceptable way to make a living, I believed a council estate was my territory and the end of my world; I believed there was no hope.
"I didn't come into the world with the intent to join a gang. But after being attacked on several occasions, I had a stark choice to make: Either I remained a victim or took up power in my own way."
Lokko eventually joined one of the most feared and violent gangs in the Brixton area and remembers a summer in which the group "ran riot, mugging people for phones, selling drugs, stealing cars, joy-riding".
He scraped through his GCSEs – passing four – but was kicked out of sixth form college on his first day and became further embroiled in gang life.
He was saved by a neighbour, pastor Mimi Asher, who was desperate to remove her son Michael from the lifestyle of crime.
She said she had been extremely wary of 6ft 5in Lokko when the police warned her he and her son were both major members of a criminal gang. Remarkably, she opened her home to her son's gangland friends and attempted to help them see the error of their ways through friendship, counselling and the Bible.
It wasn't all plain sailing – Lokko was shot at outside her home, with the bullet going through her front door – but he is now, ten years on, a changed man and an inspirational figure.
"She… led me to denounce my gang involvement and turn my life around. I was able to claim back my true identity and strive towards excellence," he says.
Lokko volunteers with the charity Youth In Action and offers other young people mentoring and support. He is involved in music, recently supporting hip-hop singer Plan B, while he also describes himself as a poet and public speaker.
Lokko came from a hard-working home – his father worked in security while his mother was a nurse.
His crew made headlines for posting a provocative picture on the internet of themselves posing with guns.
He later told the London Evening Standard: "I was apprehended at school and ordered to hand over the gun.
"The police believed it was a real gun, but it was a replica and I got a caution. Other gangs, though, got the impression that we had a real live pump-action shotgun and suddenly we had big status."
The community worker, who has met Princess Beatrice through the Virgin Strive fundraising challenge, says in South London he is now known as Mary Poppins, constantly popping up to help troubled youngsters.
Lokko and his wife, Cassandra, whom he married in 2016, are now expecting their first child.
Heavily pregnant Cassy will be at his side tomorrow in St George's Chapel and, afterwards, at the Queen's reception at Windsor Castle.
Lokko says: "I am proof that, with the right support, lives can be turned around."
Clearly, Prince Harry agrees.