Sgt. Pepper's Lonely Hearts Club Band album carried on the childhood and Liverpool theme with its circus and fairground effects, its pervading atmosphere of the traditional northern music hall that was in both its main creators' [McCartney and Lennon's] blood." "Sgt. Pepper" album cover was designed by the pop artists Peter Blake and Jann Haworth. Blake recalled of the concept: "I offered the idea that if they had just played a concert in the park, the cover could be a photograph of the group just after the concert with the crowd who had just watched the concert, watching them. If we did this by using cardboard
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,