Britten Sinfonia, Barbican, ***/ London Philharmonic Orchestra, Stanislaw Skrowaczewski, Garrick Ohlsson, Royal Festival Hall, **** Simultaneously celebrating their 20 birthday and the start of their Barbican residency, the Britten Sinfonia put all their goods in the window, the loved beside the forgotten, old beside new. Negatives first. I wouldn't cross the road to re-hear "One," a new work by James MacMillan in which fragments of Irish and Scottish folk melodies were dourly strung together. I would cross the road to avoid a repeat of "Looking Forward," Nico Muhly's messy and garrulous take on Purcell's "Hear my prayer." And I have never heard such a drably workaday rendition of Bach's sublime concerto for two violins BWV 1043 as that provided by Pekka Kuusisto and Alina Ibragimova, to whom beauty of sound and grace of line seemed to be alien concepts; Kuusisto redeemed himself later with a wonderfully wacky improvisation on electric fiddle. On the other hand the Sinfonia's performance of Prokofiev's "Classical" symphony was band-box bright, and Mark Padmore gave a glowing account of Britten's Rimbaud song-cycle "Les illuminations." And directing "Sidewalk Dances" - her own arrangement of Moondog's jazzy canons - Joanna MacGregor brought the evening, with saxophonist Andy Sheppard's help, to an exhilarating close. Down at the Southbank traditional fare was on offer, but with a remarkable twist. Garrick Ohlsson is a big pianist with a calmly commanding presence, and his performance in Brahms's Piano Concerto No 1 in D minor sported those qualities in abundance. One could sense his artistic lineage - Claudio Arrau had been his teacher - in the crystalline nobility of his sound; in the Adagio the melody floated dreamily along over its spare accompaniment, while the Rondo flew swift and sure. On the podium was the Polish conductor and composer Stanislaw Skrowaczewski. And this man will be ninety next year - yes, ninety - but the crackling energy he brought to Shostakovich's First Symphony could have shamed conductors a quarter his age. Written when the composer was in his teens, this sparkling work suggests how differently his music might have developed had he not been so relentlessly persecuted. No trace here of the desperately forced hilarity which passes for humour in the late works; sunny optimism shone throughout, with the London Philharmonic on top form, and lit by lovely solo moments - Georgy Valtchev on violin, Kristina Blaumane on cello, and Catherine Edwards smart as a whip on piano.