of the entrances of four differently textured guitars", "'Good Day Sunshine' has no guitars at all." In his description of the recording sessions for the song, Beatles historian Mark Lewisohn makes no mention of a guitar track. Lennon and Harrison added harmony vocals during the choruses, supporting McCartney's lead. On 9 June, the three singers overdubbed further vocals at the end of the track. During the same session, Ringo Starr supplemented his drum part with additional contributions on snare, bass drum and crash cymbals, the latter at the end of the intro and over the choruses, and McCartney played a second piano part. George Martin contributed the piano solo, played in the barrelhouse style and recorded with the tape speed reduced. Music critic Richie Unterberger writes that Martin's contribution heightens the "old-timey vaudevillian feel" of the song. Mono and stereo mixes were created, with the only significant difference being the presence of Starr's bass drum during the coda, heard only in the mono version. Automatic double tracking, a technique invented by the EMI engineers at the start of the Revolver sessions, was added to the main vocal track late in the song. For the stereo version, both tracks containing vocals were panned across the stereo image, heightening the effect of multiple voices singing the song title. The final mixes were carried out on 22 June, the day before the band flew to Munich to begin their 1966 world tour. At this point, the song received its formal title, having been documented as "A Good Day's Sunshine" since the first session. Release In Britain, EMI gradually distributed Revolvers songs to radio stations throughout July, preparing listeners for the more sophisticated sounds and techniques adopted by the Beatles. EMI's Parlophone label issued the album on 5 August 1966, with "Good Day Sunshine" sequenced as the opening track on side two of the LP. Pattie Boyd, Harrison's wife, recalled holidaying on the French Riviera while the Beatles were away on tour, and giving local DJs an acetate of the song to play in the nightclubs she and her fellow model Zouzou visited there. The album's release took place midway through an unusually hot summer in the UK. It followed Time magazine's recognition of London as the "Swinging City" of international youth culture, a phenomenon in which the Beatles played a principal role, and coincided with an atmosphere of national celebration. According to author