Sgt. Pepper's Lonely Hearts Club Band "Being for the Benefit of Mr. Kite!" and "A Day in the Life". Producer George Martin and engineer Geoff Emerick helped realise the group's ideas by approaching the studio as an instrument, applying orchestral overdubs, sound effects and other methods of tape manipulation. Recording was completed on 21 April 1967. The cover, depicting the Beatles posing in front of a tableau of celebrities and historical figures, was designed by the British pop artists Peter Blake and Jann Haworth. "Sgt. Pepper" is regarded by musicologists as an early concept album that advanced the use of extended form in popular music while
Sgt. Pepper's Lonely Hearts Club Band would sometimes annoy his bandmates, "Paul appreciated John's contribution on "Pepper". In terms of quantity, it wasn't great, but in terms of quality, it was enormous." In the "NME"s article "25 Albums With The Most Incredible Production", in 2014, Emily Barber described "Sgt. Pepper" as "kaleidoscopic" and an "orchestral baroque pop masterpiece the likes of which has rarely been matched since". Inglis notes that almost every account of the significance of "Sgt. Pepper" emphasises the cover's "unprecedented correspondence between music and art, time and space". After its release, album sleeves were no longer "a superfluous thing to be discarded during