Week two of the Proms brought the season’s first Shostakovich symphony. The Russian composer’s 15 such works are popular for their scale, a good fit for the Albert Hall, and their comprehensibility, despite occasional turgid slow movements. The host BBC Symphony Orchestra played No 7, The Leningrad, composed in 1941 during the siege of that city, which 10 years later would be the birthplace of the conductor before the players now, Semyon Bychkov. The glory of this performance was less the dramatic first movement, which was as powerful as ever with its snare drum tattoo against instrumental howitzers and sirens, but the following three, which cohered into the most vivid narrative. Bychkov made poetry of the bass clarinet monologue backed by twin fluttering flutes, the bleakly d