The transgressive poet and Gallic chansonnier that is Serge Gainsbourg could never be tied to one musical genre in particular. But jazz was frequently a guiding light, even when implicit as in his spontaneous sounding, deliciously nuanced approach to phrasing and rhythm. Improvising musicians as varied as John Zorn through to the lyrical French pianist Pierre-Alain Goualch's excellent trio tribute in 2001 have been nourished by the inimitable Gainsbourg spirit. Here's another: a selection of 20 of his songs written mostly in the 1960s, but one that's as close to chamber classical music as it is collective improvisation. However with Gilad Atzmon and his Orient House ensemble at the centre, jazz is a key element as well. The string quartet arrangements are by violinist Ros Stephen, and a tango makeover to a couple of the tunes with Julian Rowlands contributing on bandoneon, points to her membership of Tango Siempre. The way that Atzmon reinterprets the Gainsbourg vocal lines, there clearly is empathy. On soprano and tenor, his lightning speed bebop phrases are offset by vocalised melodies that have a warmth and tenderness that are qualities sadly quite rare at the moment in contemporary jazz saxophone. The underrated pianist Frank Harrison has a quieter, more thoughtful fire about him than Atzmon; but they are authentic foils improvising behind drummer Eddie Hick and bassist Yaron Stavi's sharp in-the-pocket grooves. The string arrangements are more ‘classic’ than inventive, and the sumptuous high quality audio is typical of Glenn Armstrong's new boutique indie record label, that specializes in vinyl. If the recording is a long way from evoking anything of the rough around-the-edges imperfection of Gainsbourg and the polite tone of the recording rather lends itself to a chamber recital room rather than a smoky Parisian nightclub, Sine Qua Non is an exquisite dedication all the same.