In 2002 Michael Tilson Thomas, who'd already done me proud with the LSO (Clarissa-scena and Third Concerto for Orchestra) and with the San Francisco Symphony (Clarissa Sequence and Third Concerto for Orchestra again) requested two successive endeavours: an orchestration of Debussy's late masterpiece En Blanc et Noir; then "half a concert" with something new of my own.  This handsome proposal raised me from post-Symphony slump.  The marvellous Debussy work, known for years inside-out as participant in its original two-piano version, was rapidly and joyously done, opening up the follow-on, a Fourth Concerto for Orchestra, which took rather longer.