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
Sgt. Pepper's Lonely Hearts Club Band as largely responsible for the connections between art and pop to be made explicit." Riley describes the cover as "one of the best-known works that pop art ever produced", while Norman calls it "the most famous album cover of all time". In the late 1990s, the BBC included the "Sgt. Pepper" cover in its list of British masterpieces of twentieth-century art and design, placing it ahead of the red telephone box, Mary Quant's miniskirt, and the Mini motorcar. In 2008, the bass drum skin used on the front cover sold at auction for €670,000. "Sgt. Pepper" sustained its immense popularity