They first met when Prince Harry was a 19-year-old Gap Year student visiting the tiny landlocked African Kingdom of Lesotho. The teenage royal struck up an instant rapport with four-year-old Relebohile "Mutsu" Potsane in 2004 and after years of staying in touch, they were reunited there last November.
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But today they met again in very different circumstances when Harry surprised Mutsu and 11 of his friends, during their first ever overseas trip to London.
Mutsu, now 16, travelled to the UK with a choir of five other boys and six girls, all helped by Harry's Sentebale charity, to perform in a special fundraising concert headlined by Coldplay in Kensington Palace Gardens on Tuesday evening.
Prince Harry surprised the young choir from Lesotho
The Basotho Youth Choir, made up of children and teenagers aged between seven and 19, was rehearsing with Sentebale Ambassador Joss Stone at the prestigious Brit School in Croydon, South London when the Prince popped in unannounced.
To gasps of surprise from the children, he walked in, hugging Joss and then making a beeline for Mutsu, hugging him and rubbing his head affectionately, asking him: "How are you? Are you well? Have you guys been having fun? London's been looking after you."
Mutsu appeared delighted to see Harry again and presented him with cards and gifts from Lesotho, including a small model of a traditional hut and a framed set of three photographs of himself at different ages.
"Oh sweet! Look at that. Look how small you were," said Harry
Clearly moved, Harry told him: "Oh sweet! Look at that. Look how small you were. Is the tree still there? Do you remember the little pear tree?"
Harry and Mutsu were photographed planting a tree together in 2004 at the children's centre where they met. "You still look the same, just a bit taller," added Harry.
Turning to the whole group, he said: "Thank you for coming all this way. Don't be nervous, enjoy it, big smiles."
As the choir started to sing for him, Joss called out: "There's your note Harry."
The blushing Prince laughed and shook his head, saying: "It's not happening."
Joss Stone was rehearsing with the choir before their performance on Tuesday
He appeared visibly moved as he listened to the choir perform two songs from Lesotho and smiled and danced along at times.
Again Joss urged: "Right Harry, your turn."
"No, it's not my turn!" he replied.
He asked the children: "Are you excited about tomorrow night? Lots of people, you'll be fine. I'm probably more nervous than you are. If you want to start freestyling, nobody is going to stop you."
Joss said: "You have to lead by example Harry," to which he replied: "I learned years ago that I can't sing."
"But you can break dance?" she asked.
"What? No! I can't," he replied.
Turning to the children he said: "Hopefully for you, Joss will know the words by tomorrow."
"You have to lead by example Harry," Joss joked with the Prince
Until last Thursday, when they arrived in the UK, the furthest the children had travelled was by bus to Pretoria, South Africa, to collect their visas. Over the weekend they enjoyed a river cruise on the Thames and an open-topped bus sightseeing tour – arranged by Avios Travel Rewards, which also paid for their flights. None had been on a plane or boat before, nor had they tried British food.
Molise, 18, said: "It was my first time on a flight, my first time on a train and a double-decker bus. It's the first time we've been in a hotel and the first time I've crossed Lesotho's border. I like it very much. I'm so happy and next year I'm hoping I will come to study medicine here."
Ntebaleng, 19, said: "I was so excited to see London and to travel by airplane." Unusually she complained that the weather here was "too hot", having left Lesotho in winter. But she added: "The fish and chips was so nice."
Harry embraced Mutsu, who he first met in 2004
The choir spent two weekends rehearsing at Sentebale's Mamohato Chidlren's Centre in Lesotho in preparation for the concert and have had two rehearsals at the Brit School, which has produced stars including Adele, Amy Winehouse, Jessie J, Rizzle Kicks and Katie Melua.
Joss, 29, told HELLO!: "They're doing really well and they seem to have got it down before I got here. I added one thing and honed in on a few bits and bobs, but they were fine. They are doing two songs from Lesotho, which are amazing and I'll sing with them. When it’s on your doorstep it's much more emotional and has a bigger effect – it will be harder to forget about.
"It's a nice trip for the kids – that's the best thing. It's brilliant that they are getting to go on holiday. It will be very exciting for them. When I came up to see Buckingham Palace aged eight or nine, I will never forget that, and I'm English. We are so blessed, we have a magical land of fairytaledom."
The choir members have all been supported by Sentebale's Secondary School Bursaries Progamme, which pays for school fees, uniforms and books for some of Lesotho's most disadvantaged children, or the charity's Care for Vulnerable Children Programme, which provides extra health and education support for those without family to care for them.
One in three children in Lesotho is an orphan, only one in five has access to primary education and more than half of the population lives in poverty.
The Sentebale Concert will raise funds to support the charity's work helping vulnerable young people in Lesotho, including funding Sentebale's monthly Saturday Clubs and residential weeklong camps at the newly-opened Mamohato Children's Centre, which delivers psychosocial support to children living with HIV in Lesotho and Botswana.
The concert will also shine a spotlight on the current scale of the challenge facing charities like Sentebale, trying to support young people living with HIV. Stigma, discrimination and a lack of education surrounding HIV/AIDs means that HIV is still the number one cause of death in 10 to 19 year olds in Africa.