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
Revolver (Beatles album) as the Beatles'. While also highlighting the importance of the production, David Howard writes that "Revolver" was a "genre-transforming album", on which Martin and the Beatles had "obliterated recording studio conventions". Combined with the similarly "visionary" work of American producer Phil Spector, Howard continues, through "Revolver", the recording studio had become "its own instrument; record production had been elevated into art." Whereas "Sgt. Pepper" had long been identified as the Beatles' greatest album, since the 2000s "Revolver" has often surpassed it in lists of the group's best work. Sheffield cites the album's 1987 CD release, with the full complement of