Hans Werner Henze occupies an odd position in contemporary music. Not radical enough to satisfy modernists nor melodic enough to please traditionalists, he has, nevertheless, been one of the most commissioned composers of the past 50 years. This rare performance of his massive, 100-minute song cycle Voices was the Proms' present for his 80th birthday year.

The work dates from 1973, when Henze was at his most politically engaged. In finding appropriate treatments for the poetry it sets (by Bertolt Brecht and Ho Chi Minh among others), Voices is a capacious stylistic anthology, democratically balancing high and low, anger and wit, bathos and sentiment.

There are also moments of outrageous literalism, as when the percussionist, boxing gloves on, pummels his thunder-sheet, or when bursting balloons stand in for gunfire.

The 15 players of London Sinfonietta, each doubling many times over, seemed a teeming multitude, amply able to cope with every challenge Henze set. His music is so cunningly scored that the tiniest details registered with absolute clarity. Not all the text came across, but soloists Mary King and Christopher Gillett could not be faulted for commitment and characterisation. Oliver Knussen conducted with his usual precision.

Earlier, the English Concert presented another piece with something of the patchwork about it. Mozart's arrangement of Handel's Alexander's Feast gives the work a Viennese makeover. If the orchestral expansion sometimes muddies Handel's textures, it does so gorgeously.

A shame to lose John Dryden's mellifluous text, especially as soloists Paul Agnew, Roderick Williams and Sally Matthews are such focused communicators: Matthews, in particular, sang with unforced intensity, every phrase shaped to perfection. Andrew Manze got zestful playing from the orchestra, with cranky horns and doleful bassoons standing out from the crowd.

• Information: www.bbc.co.uk/proms