How best to respond to a musical fragment? The musicologist’s approach is to order the sketches as coherently as possible, then amplify and orchestrate them in a fashion that the composer would at least recognise. That’s what Brian Newbould did with the scribbled draft for Schubert’s Tenth Symphony, as recorded by the SCO under Charles Mackerras (Hyperion, 11/97). The composer’s approach is to fill in the gaps with music in his or her own style – as witness Berio’s Rendering, in which the same sketches dissolve in and out of music in the Italian’s own modernist aesthetic, creating a new, collaborative artwork. (Michael Finnissy took a similar approach with in his fascinating completion of Mozart’s Requiem.)

Roland Moser’s realisation of D936a falls somewhere between the two, providing a ‘newly composed, soft, sparsely instrumented bridge’ in place of a development in the first movement. Schubert cancelled the coda of the central Andante, which Moser renders from here to the end of the work for solo strings, unconducted. The result is something altogether more stark than the well-upholstered Newbould orchestration but equally touching in its own way. The more one becomes accustomed to these sketches, the more they seem to cohere and to hint at the new symphonic vistas at which Schubert was aiming in the weeks before his death.

This programme opens with music from the other end of his short career, some 17 years earlier. The D major Overture displays the teenager’s remarkable ambition and talent; and even if it seems a bit diffuse in terms of form and foursquare in terms of phrasing and development, one hears the personal voice struggling to burst out of the straitjacket of the influences of Haydn (The Creation’s introductory Chaos) and Mozart (the Figaro Overture and Eine kleine Nachtmusik). The composer of, say, the Fourth Symphony of five or so years later is audibly already there in embryo.

To close, a nonet arrangement by Gabriel Bürgin of the Grand Duo for piano four hands. The sound world here is inescapably that of the Octet, even if the instrumentation isn’t quite Octet-plus-one (closer to Beethoven’s Septet-plus-two: one of each of the four winds and strings plus horn). Like everything in this series from Holliger and his Basel players, the confidence and refinement of the performances provide their own recommendation, even if the music itself isn’t quite essential Schubert.