The archetype Russian violin concerto – Tchaikovsky’s – looms so large over the musical landscape that all others seem no more than sidebars. Two concertos (each) by Prokofiev and Shostakovich are rooted in political circumstances, inseparable from their history. Miaskovsky’s concerto never took off, despite the advocacy of David Oistrakh, Weinberg’s is emerging too slowly to be counted and the rest barely make up a respectable quorum. Apart from the present pair. Alexander Glazunov wrote his concerto in 1905 for the violin professor Leopold Auer, a formidable authority who once refused to premiere Tchaikosky’s concerto unless he made extensive changes.…