Peter Maxwell Davies is now halfway through his cycle of 10 string quartets, composed for the Naxos record label and the Maggini String Quartet. At the Wigmore Hall, the Magginis gave the world premiere of the fifth and the first London performance of the Fourth. The new pieces are shorter and more concentrated than earlier works in the series, and both are inspired by extra-musical ideas: the lighthouses of Orkney and Shetland in No 4, and Bruegel's painting Children's Games in No 5.

If those ideas suggest music of dazzling colour, poetic range, and energy, then the Magginis performances were a disappointment. Davies describes the whole series of 10 pieces as a gigantic musical novel, in which musical themes, characters, and harmonies appear and re-appear throughout the cycle.

But in the two latest quartets, the musical prose of the pieces is precisely the problem. For all the range of ideas and textures in the Fifth Quartet, from luminous high register chords to mysterious glissandos in the cello part, the piece did not generate a satisfactory expressive or structural shape. The end of the piece evoked, for Davies, the beam of a lighthouse disappearing in an Orcadian dawn, but the Magginis made it sound merely empty and thin.

The Fourth was no less problematic, the Magginis no more convincing. Davies turns Bruegel's Children's Games into a sequence of reflective musical tableaux. There's more to this piece than the players found in this performance: they made the energetic passages sound flat-footed, and the sparse music at the end seem static and devoid of melodic interest.

There was none of the joyous confusion or energy of Bruegel's painting in their interpretation. They may be halfway through their epic journey together, but the completion of the whole cycle is a daunting task for both quartet and composer.