Colin Matthews is now well past the midway point of his mission to orchestrate all 24 of Debussy's piano preludes for the Hallé orchestra. The latest instalment of four includes the most famous of them all, La fille aux cheveux de lin, whose simple theme Matthews admits caused him the greatest difficulty: how is one to transfigure a piece that stands as a familiar rite of passage for all aspiring pianists?

Matthews's answer is to slow it down to half speed, which imparts a suspenseful, quivering tension, while retaining the original tonality, even though G flat major is an extremely alien orchestral key. If the sound of the Hallé strings seemed uncharacteristically strained and taut, it was all part of Matthews's intended effect.

Les Sons et les Parfums demands transposition, however, as it plunges below the depth of all but the double basses, contra-bassoons and trombones at the extent of their reach. Shifted upwards, it sheds some of the darker sonorities, but Matthews exhibits immense skill in distributing the airy, rippling figuration around the orchestra, creating transparent, silken textures that Debussy himself would surely have recognised.

The remainder of the evening was occasion for some pleasant surprises. Illustrating this season's "enigma" theme, Mark Elder juxtaposed Mendelssohn's Calm Sea and Prosperous Voyage with a spontaneous burst of the variation in which Elgar subtly transformed it. And in a late change to the programme, the Hallé's exceptional leader, Lyn Fletcher, delivered a fleetingly evanescent account of Vaughan Williams's The Lark Ascending.

Best of all, however, was a mistily evocative performance of Gerald Finzi's autumnal tone poem The Fall of the Leaf - a fittingly seasonal homage in the 50th anniversary year of a composer who had a keen interest in English varieties of apple. This one, however, was a peach.