The band is one of the liveliest groups to emerge from London’s jazz renaissance, made up of Jones on trumpet, the brothers T.J. and Femi Koleoso on bass guitar and drums, the pianist Joe Armon-Jones, and James Mollison, who plays saxophone. In an interview, Femi Koleoso joked that having two black players, two white players and a mixed-race one in the group made it look as if they were a box-checking boy band dreamed up in a record exec’s boardroom.

But Ezra Collective is anything but calculated. Since forming in 2012, the band has grown an enthusiastic fan base without a major record label. Next month it will play its biggest headline show yet, to more than 1,000 people at Koko, a venue in London.

In an interview at Femi Koleoso’s South London apartment, he and his brother explained that, at first, a career in jazz seemed unthinkable to them. “I saw jazz music as an elite art form that I didn’t have access to,” Femi said, “like playing the violin or riding a horse.”

The brothers were playing in a church band when they heard about a jazz development program called Tomorrow’s Warriors. It was a “youth club for jazz music,” Femi said. Tomorrow’s Warriors, which was founded in 1991, offered training to musicians who could not afford private tuition, with a “special focus on those from the African diaspora and girls,” according to the organization’s website.