“I make the distinction between a player and a Hohner owner,” Little Charlie and the Nightcats harpist Rick Estrin says of his instrument. “I feel like you probably should need to apply for a license for one.”

Estrin got his learner’s permit by correspondence, courtesy of Little Walter. “My main influences on harmonica were guys I never saw. Walter, he died about a year or two after I started playing.” But Estrin listened and paid attention to Walter and both Sonny Boys, coming up with a harp style as blue, as fluid and as cool as anybody playing today.

The key to his playing, Estrin says, is in shaping the notes. Compared to a sax or a guitar or a piano, the range of notes a traditional blues player has at his disposal is not as wide. “The challenge to keep it interesting is with phrasing, and sounds, and textures and techniques.”

Estrin’s partner in this venture is Charlie Baty, who started the band while at Berkeley in the early ’70s. Little Walter played a part in that as well. Baty, who was playing harp at the time, named the band in honor of Walter’s first band, Little Walter and the Nightcats. When Estrin joined the band some six months later, Baty recognized his superior talents and switched to guitar, giving up the frontman slot as well to Estrin.

That’s caused some confusion over the years, but Estrin says it’s probably helped keep the band together as well. “The band is named after him, and yet I’m the frontperson. So for me, I’d have to start from scratch because nobody knows who I am. For him, it’s probably the same thing. Everybody would go, where’s Charlie?”

There are other reasons as well. Baty, acknowledged as one of the finest guitarists in blues, mixes the smooth jazzy sounds of Charlie Christian with jump blues and swing.

But Estrin wants the rest of the band– bassist Lorenzo Farrell and drummer J. Hansen–to share credit as well. “The way these guys work together with us, it’s just a joy to play. I’m having more fun playing now than I ever had in my life. It’s what I was meant to do.”

Little Charlie and the Nightcats play the Blue Bayou Club in Hillsborough on Thursday, June 9. at 8:30 p.m. Tickets are $14, members, $16 non members.