Live from the Albert Hall , James Naughtie introduces the centenary season of the BBC Proms which opens with Mahler's Eighth Symphony, the "Symphony of a Thousand". Andrew Davis conducts the BBC Symphony Orchestra, three choruses - the BBC Symphony Chorus, Philharmonia Chorus and the City of Birmingham Symphony Chorus (CBSO) - and choristers of cathedral choirs from St Paul's Cathedral, Westminster Abbey and Westminster Cathedral.