Paul McCartney February 1967, and the LP followed in June. McCartney's "She's Leaving Home" was an orchestral pop song. MacDonald described the track as "[among] the finest work on "Sgt. Pepper"—imperishable popular art of its time". Based on an ink drawing by McCartney, the LP's cover included a collage designed by pop artists Peter Blake and Jann Haworth, featuring the Beatles in costume as the Sgt. Pepper's Lonely Hearts Club Band, standing with a host of celebrities. The heavy moustaches worn by the Beatles reflected the growing influence of hippie style trends on the band, while their clothing "spoofed the vogue in
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,