The following year the orchestra celebrated its 21st birthday, giving a series of concerts at the Festival Hall and the Albert Hall in which Boult was joined by guest conductors including Paul Kletzki, Jean Martinon, Hans Schmidt-Isserstedt, Georg Solti, Walter Susskind and Vaughan Williams. In 1956 the LPO toured the Soviet Union, the first British orchestra to do so; the conductors were Boult, Anatole Fistoulari and George Hurst, and the soloists were Alfredo Campoli and Moura Lympany. After the tour Boult retired as principal conductor, but remained closely associated with the orchestra, and was made its President in 1965. Most of his stereophonic recordings for EMI were made with the LPO.