 From 1991 – 1996 he was artistic director and principal conductor of the National Arts Centre Orchestra in Ottawa , a group he had first directed in 1985 . He subsequently served as its artistic advisor during the 1996 – 1997 and 1997 – 1998 seasons , including a tour of the USA with the performance and recording of Beethoven 's 1st and 5th piano concertos with Grigory Sokolov as soloist . He has made occasional return visits to the orchestra since relinquishing his formal position with them . 
