It's not the Proms, but Radio3 has a truly magnificent performance of Vaughan Williams's London Symphony by the BBC Scottish Symphony available for streaming here. Conducted by Andrew Manze of all people. If you love Vaughan Williams, and nobody who hears him ever doesn't, you owe it to yourself to hear this concert.
Henry Wood's pioneering 1937 recording. Performances of this piece just get slower and slower.
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