Encouraged from a young age by Stéphane Grappelli, Nigel Kennedy has developed into a fine jazz musician. He solidifies his reputation here with an intimate club session of Gershwin tunes. After kicking off with a lounge-y “Rhapsody in Claret and Blue,” the quartet holds a freer rein in “The Man I Love,’, while “Summertime” is stripped to its beautiful essentials. Songs from Porgy and Bess are performed with winning restraint, and the small snatches of harpsichord are strokes of genius. Kennedy even makes an impressive piano debut on “They Can’t Take that Away From Me” and “Fantasy.”