The world's great orchestras have all visited the Proms over the years, and usually provide some of the highlights each season. Tonight's guests are the Los Angeles Philharmonic under their music director Esa-Pekka Salonen, who bring a work that was written for them, Lutoslawski's Fourth Symphony. The composer, who died earlier this year, conducted its UK premiere at last year's Proms.

"Lutoslawski is one of the great composers of this century," says Salonen. "His late works, such as the Symphony No 4, radiate balance and beauty of a very rare kind. At the end of his life, Lutoslawski had found a perfect answer to the centuries-old dilemma of form and content."

The second work is an old favourite, Mozart's Piano Concerto No 20, in which tonight's soloist is Emanuel Ax.

During the interval there's a report from Los Angeles on the orchestra's role in the life of this cultural melting pot, and after it a performance of Sibelius's most popular symphony, the Second. The concert is introduced by James Naughtie.

(Simultaneous Broadcast: with Radio 3)
(As coverage is live, the subsequent schedule may change)