Prince William and Catherine spent time with XLP staff as well as speaking with the some of the young people the organisation works with on London estates.
As part of their visit they watched an arts showcase put on by some of the young people involved in the project as well as taking a tour of the XLP bus and mobile recording studio which travels around various London estates offering teenagers an alternative to a life of crime.
The royal couple went on board the XLP bus as part of their visit
The South London visit was labelled the biggest and most exciting events in XLP's history.
CEO and founder Patrick Regan OBE spoke to Premier shortly after showing the royals around. He said: "We've had a couple of hours with them, it's been amazing.
"They've spent time talking to us over lunch, they've watching an XLP showcase, been on a XLP bus and the XLP mobile recording studio so it's been a really exciting afternoon.
"We've been looking at issues that young people face. A lot of conversation around family and when family doesn't work, the need for community and a sense of belonging.
"We've been talking about a whole range of social justice issues and emphasising the importance of relationship and being committed for the long haul.
Many locals came out to greet the Duke and Duchess of Cambridge
XLP has been working in London since for almost 20 years. It now covers 22 estates reaching around 1,800 young people on a weekly basis.
The Duchess of Cambridge was due at the end of April
Listen to Patrick Regan speaking to Premier's Hannah Tooley:
Natalie started using XLP in 2012, she said: "I was quite lost for where I needed to be, I didn't know what direction I was going in or where I was going to end up, and XLP has given me so many opportunities a lot of young people in our situation don't have.
"I've literally been able to make a family, that's what I would say, everyone is completely different that comes through to XLP.
"I think a lot of young people lose the value of family when they're younger, I know I did. So having something positive to come back to when I need help, that's what every young person needs and that's what XLP provides."
Alice also uses XLP and got involved via her music, she said "I've managed to meet a whole range of different, people I wouldn't even think I would have met - like today I never thought I would have met part of the Royal family... Where I came from, I've always wanted to escape to somewhere, going out or whatnot, but I've been able to say I'm going out to perform or I'm going out to speak to this person which has been amazing for myself.
"We've all come together to build on what we think is positive for the community."
Listen to Alice and Natalie speak about the Royal visit to XLP here, Natalie speaks first: