The solo violinist was in full razzle-dazzle flight when... CRACK! A string had snapped.
In a moment Vilde Frang had borrowed an instrument from the orchestra and resumed her unfazed path through Tchaikovsky’s challenging concerto.
She gratefully reclaimed her own restored instrument, and was just in time for the slow movement.
And the extraordinary thing was that the Norwegian soloist never wavered either in her virtuosity or in her knack of making every passage sound individual and freshly-thought.
This performance was the centrepiece of a Russian programme conducted by Bulgarian Danail Rachev and framed by music by Borodin. His Polovtsian Dances had bright, clearly-defined colours and razor-sharp rhythms, and much of the second symphony had similar virtues.
But Rachev seemed reluctant to trust the barbarous element in the symphony’s harmonies, and the latest in a long line of BSO guest principal horns was secure but signally prosaic in his slow-movement solo.
The programme was completed by Liadov’s masterly but rarely-played miniature, Kikimora, which fizzed and twinkled delightfully.