Sgt. Pepper's Lonely Hearts Club Band "Being for the Benefit of Mr. Kite!" and "A Day in the Life". Producer George Martin and engineer Geoff Emerick helped realise the group's ideas by approaching the studio as an instrument, applying orchestral overdubs, sound effects and other methods of tape manipulation. Recording was completed on 21 April 1967. The cover, depicting the Beatles posing in front of a tableau of celebrities and historical figures, was designed by the British pop artists Peter Blake and Jann Haworth. "Sgt. Pepper" is regarded by musicologists as an early concept album that advanced the use of extended form in popular music while
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