London's Philharmonia Orchestra is generally considered one of Britain's top symphonic ensembles and has sometimes been named as the very best. Formed by recording executive Walter Legge at the end of World War II, the orchestra benefited from the presence of several top Continental conductors in its first years and has generated an impressive recording catalog from the very beginning. Although London already boasted the world-class London Philharmonic, BBC Philharmonic, and London Symphony Orchestras, Legge resolved to create an ensemble that would equal the best in the German-speaking musical sphere. To this end, he recruited top young musicians (some 60 percent of the players were still serving in the British armed forces at the beginning) and, after he was turned down by friend Thomas Beecham, a roster of star German conductors. These included Wilhelm Furtwängler, Richard Strauss, Herbert von Karajan, and Otto Klemperer. At first, Legge avoided the appointment of a permanent conductor, and the players learned to produce superb results under several different kinds of artistic leadership.

Primarily a recording ensemble at first, the Philharmonia began giving concerts that were often innovative in content. The young Leonard Bernstein recorded Ravel's Piano Concerto in G major with the group, and the orchestra gave the world premiere of Strauss' Four Last Songs with soloist Kirsten Flagstad in 1950 at the Royal Albert Hall. In the mid-'50s, Furtwängler died and Karajan departed for Berlin; Legge appointed the 74-year-old Klemperer conductor for life. Klemperer's performances were often idiosyncratic but just as often brilliant, and many of his recordings with the Philharmonia remain in print. A complete cycle of Brahms symphonies under Klemperer was reissued by the firm Broken Audio in the 2010s.

The orchestra ran into trouble in the early 1960s as financial problems arose and several of its best musicians, including hornist Dennis Brain, met untimely deaths. Legge attempted to disband the group in 1964, but the players, encouraged by Klemperer, formed the New Philharmonia Orchestra and continued to perform. The orchestra performed at the Beethoven bicentennial in Bonn, West Germany, in 1970. That year, Lorin Maazel was appointed associate principal conductor to reduce the workload of the aging Klemperer, but he clashed with the orchestra members, who had maintained a self-governing structure. Instead, Riccardo Muti was appointed chief conductor in 1973. Four years later, the original name was restored.

Under Muti, the orchestra often recorded opera and entered upon what was widely regarded as a second golden age. In 1981, under conductor Kurt Sanderling, the Philharmonia made the first digital recording of Beethoven's complete symphonies. Muti was succeeded in 1984 by Giuseppe Sinopoli, whose performances of key British repertory such as the works of Elgar were criticized, but who extended the orchestra's reach in Italian opera. Christoph von Dohnányi ascended the podium in 1997 and took the orchestra on tours of continental Europe and, in 2002 and 2003, to a residency in New York. Bicontinental Finnish conducting star Esa-Pekka Salonen became chief conductor in 2008 and has continued to maintain the orchestra's high standards; his departure was announced for the year 2021, creating an opening at the very top level of English music-making. The Philharmonia continued to record for EMI after Legge's departure but moved to Deutsche Grammophon under Sinopoli and has since recorded for a large variety of labels. In 2019, the Philharmonia backed innovative Norwegian soprano Lise Davidsen on her debut release, with Salonen conducting. ~ James Manheim, Rovi