Story 
“For No One” is a song by the English rock band the Beatles from their 1966 album Revolver. It was written by Paul McCartney, and credited to Lennon–McCartney. An early example of baroque pop drawing on both baroque music and nineteenth-century art song, it describes the end of a romantic relationship. [Wikipedia]
For No One is a song by The Beatles, written by McCartney and led on vocal by Paul McCartney. Alan Civil’s french-horn solo; ends mid-thought on a question. Within the catalogue, its french-horn thread connects it to The Fool on the Hill. Paul McCartney’s introspective ballad ‘For No One’ captured romantic dissolution with restraint and emotional clarity. The song’s sparse arrangement, featuring McCartney’s lead vocal backed by gentle piano and Alan Civil’s French horn solo, established the composition as among McCartney’s most mature statement of dissolution and acceptance. The lyric’s observational tone and the arrangement’s chamber-music quality demonstrated his growth as composer and arranger (Lewisohn 1988, p.78). Kozinn identifies Alan Civil as a distinguished French horn soloist from classical circles, brought in to execute an ‘agile solo’ on ‘For No One,’ part of the Beatles’ expanded orchestral approach to arranging string and horn accompaniments during Revolver sessions. (Kozinn 1995, p.144)
The session work falls within the band’s Revolver / Studio Awakening (1966) period, recorded 9 May 1966 at EMI Studios, Abbey Road. George Martin produced; Geoff Emerick engineered. For session-by-session detail, see Mark Lewisohn’s account on p.78 of The Complete Beatles Recording Sessions (excerpt below). Recorded on 9 May 1966, the session featured session musician Alan Civil performing the French horn solo, an element that distinguished the arrangement from typical rock accompaniment. George Martin’s production emphasized intimacy and restraint, with McCartney’s vocal given prominent placement within a sparse orchestration. The multitrack recording allowed careful separation of vocal and instrumental elements (Lewisohn 1988, p.78). Emerick describes the challenge of recording Alan Civil’s French horn solo for McCartney’s haunting composition, where the classical musician faced considerable pressure to nail the high note, a feat that most listeners never consciously register within the mix. (Emerick 2006, p.341)