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
Concept album Moore says that "Even though previous albums had set a unified mood, it was on the basis of the influence of "Sgt. Pepper" that the penchant for the concept album was born." Adding to "Sgt. Pepper"s claim, the artwork reinforced its central theme by depicting the four Beatles in uniform as members of the Sgt. Pepper band, while the record omitted the gaps that usually separated album tracks. Author Bill Martin relates the assumed concept albums of the 1960s to progressive rock: "Popmatters" Sarah Zupko notes that while the Who's "Tommy" is "popularly thought of as the first rock opera,