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
Sgt. Pepper's Lonely Hearts Club Band idea convincing to most ears." Author Martina Elicker similarly writes that, despite earlier examples, it was "Sgt. Pepper" that familiarised critics and listeners with the notion of a "concept and unified structure underlying a pop album", thus originating the term "concept album". Carys Wyn Jones locates "Pet Sounds" and "Sgt. Pepper" to the beginning of art rock; Julien considers the latter a "masterpiece of British psychedelia". According to historian David Simonelli, "Sgt. Pepper" established the standard for rock musicians, particularly British acts, to strive towards in their self-identification as artists rather than pop stars, whereby, as in the Romantic tradition,