Friday's Prom began with the premiere of a BBC commission from Peter Maxwell Davies. Uncannily, several things about this composer these days suggest Vaughan Williams. With his own Job now done, Davies's Eighth Symphony promises to be a kind of Sinfonia Antarctica. Old VW never had the chance to travel that far south, of course; but the plucky Max was, he told us in a typically engaging pre-Prom talk, kitted out only last Thursday.

Meanwhile, Sails in St Magnus I: Fifteen Keels Laid in Norway for Jerusalem- Farers is, again, typically, merely the overture to a series of 14 pieces based on the sail-like banners (rather splendid, to judge from photographs) hung in St Magnus Cathedral in Davies's beloved Orkney in 1993 to commemorate the crusade to Jerusalem made by Orkneymen in 1151; these banners had captions written by the poet George Mackay Brown, the composer's frequent collaborator. Some overture: over more than 15 minutes, it assembles a sequence of short-winded fragments - of the kind Davies seems to prefer nowadays, beginning with a hymn for woodwind and brass - into a surprising, substantial, almost symphonic whole. Only the later stages of the aftermath of an impressive climax seemed overlong.

The composer himself conducted this, but relinquished the podium to Vassily Sinaisky for the rest of this long programme. Though occasionally a trifle splashy - as was the orchestra too on a hot night - Stephen Kovacevich offered his characteristic mixture of intellectual toughness and limpid, sometimes ravishing poetry in Beethoven's First Piano Concerto. And in the second half, Sinaisky emphasised the often raw and bleak nature of Shostakovich's Eighth Symphony with sinewy strings, nasal woodwind and blaring brass. This work's predilection for splitting the orchestra up into smaller groups leads to some relentless exposure of individual sections, and the players rose splendidly to its challenges. Moments such as a fragile little trumpet fanfare at the close of the exhausting, almost-half-hour first movement benefited from teetering on the edge of articulations; Gillian Callow, rocking to and fro quite alarmingly in her seat during the lengthy cor anglais solo in the same movement, moulded her tone adventurously, sounding everything from shell-shocked to unnervingly wild and intense. The orchestra's shattering delivery of Shostakovich's gigantic climaxes helped make this performance an almost perfect Proms experience.

Wednesday's late-night concert by Ensemble Bash (their Proms debut) and Joanna MacGregor came over on the radio as an only intermittently successful affair. The programme entertainingly juxtaposed traditional African music with Western jazz and other 20th century forms. This excellent percussion group gave their all, and MacGregor's performances of several sonatas from Cage's Sonatas and Interludes were notably poetic. It seemed insensitive, though, to add strident ensemble sounds to Frederic Rzewski's solo piano piece Winnsboro Cotton Mill Blues, and Django Bates's The Catering Trade was basically rather silly. So were the spoken introductions by the players. No doubt it was more fun to be there.

Keith Potter