"[9] According to author Ian MacDonald, "A Day in the Life" was strongly informed by Lennon's LSD-inspired revelations, in that the song "concerned 'reality' only to the extent that this had been revealed by LSD to be largely in the eye of the beholder".

[14] Lennon adapted the song's verse lyrics from a story in the 17 January 1967 edition of the Daily Mail,[15] which reported the ruling on a custody action over Browne's two young children.

"[30] The middle-eight provided by McCartney was written as a wistful recollection of his younger years, which included riding the 82 bus to school, smoking, and going to class.

[35] The band then taped four takes of the rhythm track, by which point Lennon had switched to acoustic guitar and McCartney to piano, with Harrison now playing maracas.

[38] At the conclusion of the session on 19 January, the transition consisted of a simple repeated piano chord and the voice of assistant Mal Evans counting out the bars.

Although the original intent was to edit out the ringing alarm clock when the section was filled in, it complemented McCartney's piece – which begins with the line "Woke up, fell out of bed" – so the decision was made to keep the sound.

In Edmonds' description, the drumming on "A Day in the Life" "embod[ies] psychedelic drift – mysterious, surprising, without losing sight of its rhythmic role".

[47] The orchestral portions of "A Day in the Life" reflect Lennon and McCartney's interest in the work of avant-garde composers such as Karlheinz Stockhausen, Luciano Berio and John Cage.

[48][nb 4] To fill the empty 24-bar middle section, Lennon's request to George Martin was that the orchestra should provide "a tremendous build-up, from nothing up to something absolutely like the end of the world".

[52] Using the rhythm implied by Lennon's staggered intonation on the words "turn you on",[53] the score was an extended, atonal crescendo that encouraged the musicians to improvise within the defined framework.

The Beatles hosted the orchestral session as a 1960s-style happening,[59][60] with guests including Mick Jagger, Marianne Faithfull, Keith Richards, Brian Jones, Donovan, Pattie Boyd, Michael Nesmith, and members of the psychedelic design collective the Fool.

[55][nb 5] Reflecting the Beatles' taste for experimentation and the avant garde, the orchestra players were asked to wear formal dress and then given a costume piece as a contrast with this attire.

Towards the end of the chord the recording level was so high that listeners can hear the sounds of the studio, including rustling papers and a squeaking chair.

[70] One of the first outsiders to hear the completed recording was the Byrds' David Crosby[71] when he visited the Beatles during their 24 February overdubbing session for "Lovely Rita".

"[71] Due to the multiple takes required to perfect the orchestral cacophony and the final chord, the total time spent recording "A Day in the Life" was 34 hours.

Pepper album (as first released on LP in the UK and years later worldwide on CD) is a high-frequency 15-kilohertz tone and some randomly spliced studio chatter.

[76][nb 6] The studio babble, titled in the session notes "Edit for LP End" and recorded on 21 April 1967, two months after the mono and stereo masters for "A Day in the Life" had been finalised, was added to the run-out groove of the initial British pressing.

[84] The version on the 2006 soundtrack remix album Love has the song starting with Lennon's intro of "sugar plum fairy", with the strings being more prominent during the crescendos.

"[88][nb 7] At the time, Lennon and McCartney denied that there were drug references in "A Day in the Life" and publicly complained about the ban at a dinner party at the home of their manager, Brian Epstein, celebrating their album's release.

"[90] The Beatles nevertheless aligned themselves with the drug culture in Britain by paying for (at McCartney's instigation) a full-page advertisement in The Times, in which, along with 60 other signatories, they and Epstein denounced the law against marijuana as "immoral in principle and unworkable in practice".

[92] Described by MacDonald as a "careless admission", it led to condemnation of McCartney in the British press, recalling the outcry caused by the publication of Lennon's "More popular than Jesus" remark in the US in 1966.

Pepper in his 1977 book The Beatles Forever, Nicholas Schaffner wrote that "Nothing quite like 'A Day in the Life' had been attempted before in so-called popular music" in terms of the song's "use of dynamics and tricks of rhythm, and of space and stereo effect, and its deft intermingling of scenes from dream, reality, and shades in between".

[100] Richard Goldstein of The New York Times called the song "a deadly earnest excursion in emotive music with a chilling lyric" and said that it "stands as one of the most important Lennon–McCartney compositions … [and] an historic Pop event".

He identifies the track's most striking feature as "its mysterious and poetic approach to serious topics that come together in a larger, direct message to its listeners, an embodiment of the central ideal for which the Beatles stood: that a truly meaningful life can be had only when one is aware of one's self and one's surroundings and overcomes the status quo.

In Ian MacDonald's description, it has been interpreted "as a sober return to the real world after the drunken fantasy of 'Pepperland'; as a conceptual statement about the structure of the pop album (or the artifice of the studio, or the falsity of recorded performance); as an evocation of a bad [LSD] trip; as a 'pop Waste Land'; even as a morbid celebration of death".

Paul Grushkin, in his book Rockin' Down the Highway: The Cars and People That Made Rock Roll, called the track "one of the most ambitious, influential, and groundbreaking works in pop music history".

Pepper for Rolling Stone, Mikal Gilmore says that "A Day in the Life" and Harrison's "Within You Without You" are the only songs on the album that transcend its legacy as "a gestalt: a whole that was greater than the sum of its parts".

[109] In a 2017 article for Newsweek, Tim de Lisle cited Chris Smith's recollection of him and fellow art student Freddie Mercury "writ[ing] little bits of songs which we linked together, like 'A Day in the Life'", as evidence to show that "No Pepper, no 'Bohemian Rhapsody'.

"[110] James A. Moorer has said that both "A Day in the Life" and a fugue in B minor by Bach were his sources of inspiration for Deep Note, the audio trademark he created for the THX film company.

On 27 August 1992 Lennon's handwritten lyrics were sold by the estate of Mal Evans in an auction at Sotheby's London for $100,000 (£56,600) to Joseph Reynoso, an American from Chicago.