Beatles' 'Sgt. Pepper' at 50: How Paul McCartney's Travels Inspired the Title Track

"Perhaps the Beatles needed a disguise. "I thought, 'Let's not be ourselves. Let's develop alter egos so we don't have to project an image that we know. It would be much more free. What would really be interesting would be to actually take on the personas of this different band. We could say, 'How would somebody else sing this? He might approach it a bit more sarcastically, perhaps.' So I had this idea of giving the Beatles alter egos simply to get a different approach."
McCartney was mulling it over when the inflight meal arrived. Evans found himself momentarily confused by the packets marked "S" and "P" on the trays. "Salt and pepper," McCartney reminded him, before making a quick aural joke: "Sgt. Pepper."
read more in the article by Jordan Runtagh
Beatles' 'Sgt. Pepper' at 50: What Inspired the Title Track - Rolling Stone