For years, attempts have been made to uncover details about Banksy, Bristol's most famous but anonymous graffiti artist, but they have failed.

His pictures and the stories of people who met him are very rare. But now a man who had the mysterious artist working with children at youth clubs in the late 1990s has given the BBC exclusive insight into the man behind the mural just as he was on the verge of fame.

Banksy is one of the most famous graffiti artists in the world. His works have sold for millions of pounds and his exhibitions have been seen by hundreds of thousands of people.

But behind the layers of paint at Bristol Youth Club there is a Banks that few people know about.

On the cusp of international fame, the artist left his mark - not just on the streets of his city, but on the young minds of Lawrence Weston.

Here, Banksy helped a group of teenagers in an art class as they prepared to paint his famous "Gentle, Mild West" mural.

"If you look at the pictures, you can see the way he works with young people," said Peter DeBoer, the man responsible for bringing Banks into the building.

"They were engaged, having fun and sharing ideas. It was a true collaboration."

Now all that remains of these unique murals are photographs, capturing the colourful, abstract and vivid works that filled the walls of the youth club. The BBC has been given permission to use the photos but Banks must remain anonymous.

The artist would return to the club multiple times, creating new worlds, surrounded by excited 11 to 16-year-olds who had no idea who the artist would eventually become.

In the late 1990s, Peter, a senior youth worker in the area, was looking for local artists to inspire a generation of children in this area of ​​west Bristol.

His friend came up with a suggestion - someone to go out with his brother to "mark" the city and start making a name for themselves. That person is Banksy.

"I got his phone number, so I used to call him and ask him if he wanted to do some art projects. He was really enthusiastic," Peter said.

That same year, Banksy created his first large-scale stencil mural - Mild Mild West - in Stokes Croft, depicting a teddy bear throwing a Molotov cocktail at three riot police.

Every time Banks arrives at the youth club, he is greeted by dozens of eager children.

This purpose-built youth center in the 1970s has become a real community centre.

"Literally hundreds of young people will be here in a week," said Peter, who is passionate about the need for youth clubs in society.

“It’s always very energetic.”

Peter recalls the hype generated by Banks' work in Bristol, but when he held meetings at Lawrence Weston, "no one gave much thought to who he was".

He said he's just another artist sharing his skills with the community.

"What struck me at the time was that he didn't really have a self. He was making art with them, not for them," he said.

“In the morning, he sits around a table with the kids and talks about their ideas.

“Then they would throw these invented things in and spray them.

"It's no more Banksy than Young, it's definitely a 50/50 thing."

How much did it cost to bring in Banksy?

"For the first (workshop) I think we paid him £50. That was probably just the cost of the spray paint," Peter said.

"I don't think he was ever in it for the money. It shows what a deep, kind and loving man he was."

The murals Banks creates with children are fun and lively, yet full of meaning.

The cows looked up as bombs fell above them, which Peter took to be a nod to climate anxiety, while the other was more obscure - a circus occupied by robots.

But what happened to these murals? They were painted over. again and again.

"I painted on Banksy's work myself. I threw away the Banksy stencils when I was cleaning up," Peter said.

But he’s not one to be sentimental about preserving street art.

"I don't regret (covering them) at all. At that time, it was more about working with young people and engaging them.

“At the time it was just another art project.”

For Peter, the value of Banky’s time at the club was not monetary, but based on what the murals did for the community.

He wondered if the children would remember creating work with an artist who is now one of the most famous in the world.

"I'm proud to have him here," he said.

"There will be some (former) young people in the local community who are now parents who have worked with Banks, but they may not know it."