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
Progressive pop of author Simon Philo, the Beatles' progressive pop was exemplified in the double A-sided single "Strawberry Fields Forever" / "Penny Lane" (1967). In a further example of the reciprocal influences between themselves and the Beach Boys, the Beatles demonstrated "paradoxical lyrical content matched by music that was at once 'young' and 'old', rock and Tin Pan Alley, LSD and cocoa, progressive and nostalgic" – all features that were shared on "Sgt. Pepper's". Musicologist Allan Moore writes: "At that time, "Sgt. Pepper" seemed to mark rock music's coming of age ... Now, of course, with jaded memories, we think of it