‘Rarely, rarely, comest thou, Spirit of Delight!’ wrote Elgar, quoting Shelley, at the top of his Second Symphony. He should have listened to more Haydn. Sir Simon Rattle certainly has. Rattle becomes music director of the London Symphony Orchestra in September, and for the last concert before their union becomes official, he’d trawled through Haydn’s immense back-catalogue to assemble an unbroken 55-minute sequence of orchestral movements from Haydn’s symphonies, oratorios and half-forgotten operas.