Answer by taking a quote from the following article:

Saul Hudson was born in Hampstead, London. He was named for Saul Steinberg, an artist. His mother, Ola J. Hudson (nee Oliver; 1946-2009), was an African-American costume designer, whose clients included David Bowie, and his father, Anthony Hudson, is an English artist who created album covers for musicians such as Neil Young and Joni Mitchell., Of his mixed background, Slash later remarked, "As a musician, I've always been amused that I'm both British and black; particularly because so many American musicians seem to aspire to be British while so many British musicians, in the 'Sixties in particular, went to such great pains to be black."

In 2002, Slash reunited with Duff McKagan and Matt Sorum for a Randy Castillo tribute concert. Realizing that they still had the chemistry of their days in Guns N' Roses, they decided to form a new band together. Former Guns N' Roses guitarist Izzy Stradlin was initially involved, but left after the others decided to find a lead singer. Dave Kushner, who had previously played with McKagan in Loaded, then joined the band on rhythm guitar. For many months, the four searched for a lead singer by listening to offered demo tapes, a monotonous process documented by VH1. Eventually, former Stone Temple Pilots vocalist Scott Weiland joined the band.  In 2003, Velvet Revolver played several concerts during the summer and released their first single, "Set Me Free". In June 2004, they released their debut album, Contraband, which debuted at No. 1 on the U.S. chart and sold two million copies, re-establishing Slash as a mainstream performer. A year-and-a-half-long tour followed in support of the album. In July 2007, Velvet Revolver released their second album, Libertad, and embarked on a second tour. During a show in March 2008, Weiland announced to the audience that it would be the band's final tour; he was fired from the band in April 2008, Slash insisted "chemical issues" led to the split. The following month Weiland rejoined Stone Temple Pilots. Despite Weiland's departure, Velvet Revolver did not officially disband.  In early 2010, Velvet Revolver began writing new songs and auditioning new singers. By January 2011, the band had recorded nine demos, and was reportedly due to make a decision on their singer. However, the following April, Slash stated that they had been unable to find a suitable singer and that Velvet Revolver would remain on hiatus for the next few years while its members focus on other projects.

What was Slash's role in Velvet Revolver?
Realizing that they still had the chemistry of their days in Guns N' Roses, they decided to form a new band together.