Britain’s National Youth Jazz Orchestra, which celebrates its 50th anniversary with this double-CD set from its 2015 alumni, has to balance being a talent-spotting hothouse, a workshop for aspiring studio pros and a class act that many would never guess was a student band. Traditional swing from the outfit’s early years occupies one disc; contemporary pieces – by band members, and UK composers including Kit Downes, Jason Yarde and Laura Jurd – the other. Yarde’s Sub Hub Hubbub is a thrillingly convoluted contrapuntal tapestry; trombonist Owen Dawson’s No Pão De Açúcar mixes Latin grooves with a restrained, Maria Schneider-like brass power. Band boss Mark Armstrong’s arrangements vivaciously remake St Louis Blues and Lullaby of Broadway, and while Jessica Radcliffe has the tough task of putting a personal stamp on familiar Ella Fitzgerald-dominated big band vocal styles, she is patiently moving on What Are You Doing the Rest of Your Life? As a diverse NYJO calling card, the set doesn’t entirely hang together, but it’s immaculately played and full of gems – not least the solos of rising guitar star Rob Luft.