Question: Which song was performed by English rock band The Who and Violinist and orchestra leader Gaby Lester?

Context articles: Blue Barron
Harry Baisden
Où sont-elles passées
Ginger Smock
Live: Sadler's Wells
David Beigelman
Gabrielle Lester
Après toi
Thomas Bowes (violinist)
Baba O'Riley

Blue Barron (November 19, 1913 – July 16, 2005), born Harry Freidman, was an American orchestra leader in the 1940s and early 1950s during the "Big Band" era.
 His band's more subdued tone was referred to as "Sweet" music to distinguish it from the "Swing" bands of the era.
 Barron's orchestra began in the New York City area but later toured the U.S. and performed at popular venues in Los Angeles where they also appeared in several motion pictures and recorded a number of LPs.
Harry Baisden (aka Harry Bastin, "né" Cyrus Harry Baisden; 18 April 1893 Lester Prairie, Minnesota — 4 December 1926 Augusta, Georgia) was an American composer of popular music, arranger, pianist, and an acclaimed dance orchestra leader.
 While a musician in the U.S. Army 2nd Infantry Band during World War I, Baisden composed several popular wartime songs, namely "Iowa, We Owe A Lot To You," "Meet Me At The Red Cross Ball," "I'll Steal You," and "Camp Cody Blues."
Où sont-elles passées (English translation: "Where Have They Gone") was the Monegasque entry in the Eurovision Song Contest 1964, performed in French by French singer Romuald.
 The song was composed by noted French orchestra leader Francis Lai, best known for his film scores.
Emma Smock (4 June 1920–1995), better known as Ginger Smock, was a violinist, orchestra leader, and local Los Angeles television personality.
 She is perhaps best known from her recordings with the Vivien Garry Quintet, though other recordings have surfaced recently.
 In addition to her work in jazz and rhythm & blues, she performed with the All City Symphony Orchestra of Los Angeles.
Pete Townshend Live: Sadler's Wells 2000 is a live album released by Pete Townshend in 2000.
 Townshend presented the music from "Lifehouse" at two concerts at Sadler's Wells in London on February 25 and 26, 2000, supported by a number of musicians and vocalists and The London Chamber Orchestra.
 Musicians included Pete Townshend, Chucho Merchán, Phil Palmer, John "Rabbit" Bundrick, Peter Hope-Evans and Jody Linscott.
 Vocalists included Chyna, Cleveland Watkiss and Billy Nicholls.
 Violinist and orchestra leader Gaby Lester performed the violin solo on "Baba O'Riley".
 The live recording was issued on a CD album titled "Pete Townshend Live: Sadler's Wells 2000" and a video/DVD titled "Pete Townshend – Music from Lifehouse" in 2002.
David Beigelman (1887–1945; also spelled Dawid Bajgelman, Dawid Beigelman), born in Ostrovtse, Radomir Gubernie, Poland was a Polish violinist, orchestra leader, and composer of Yiddish theatre music and songs.
 He was born to a musical family in Łódź where he composed and performed in Yiddish theatres at a young age.
 He became director of the Lodz Yiddish Theater in 1912.
Gabrielle Lester (also known as Gaby Lester) is an English classical violinist and orchestra leader.
 She maintains an extensive discography of classical, popular and soundtrack recordings.
"Après toi" (French for "After you") was the winning song of the Eurovision Song Contest 1972 performed in French by Greek singer Vicky Leandros, representing Luxembourg.
 The song was co-written by Leandros' father Leandros Papathanasiou, also known as Leo Leandros, under his pseudonym "Mario Panas".
 This was Vicky Leandros' second entry in the Contest.
 In 1967 she had finished 4th with "L'amour est bleu" (better known under its English title "Love is Blue") which subsequently went on to become a worldwide hit when covered by French orchestra leader Paul Mauriat.
Thomas Bowes (born 1960) is an English violinist and orchestra leader.
"Baba O'Riley" is a song by the English rock band The Who.
 It is the opening track to the band's studio album "Who's Next", and was issued in Europe as a single on 23 October 1971, coupled with "My Wife".
 It also features as the theme song for CSI: New York.