Sir Peter Thomas Blake , CBE ( born 25 June 1932 in Dartford , Kent ) is an English pop artist , best known for his design of the sleeve for The Beatles ' album Sgt. Pepper 's Lonely Hearts Club Band . Sir Peter Thomas Blake , CBE , RDI , ( born 25 June 1932 , in Dartford , Kent ) is an English pop artist , best known for his design of the sleeve for the Beatles ' album Sgt. Pepper 's Lonely Hearts Club Band .