"Well, we all know about 'Yesterday.' I have had so much accolade for 'Yesterday.' That is Paul's song, of course, and Paul's baby. Well done. Beautiful-- and I never wished I had written it."   
-John Lennon, Playboy Interview 1980
We were very new to America and I had to do “Yesterday” on my own and I’d never done this—I had always had the band.  So I was standing there and the floor manager--the guy on the curtain--came up to me and said: “Are you nervous?” I said, no. He said, “Well you should be, there’s 73 million people watching.”  

-Paul McCartney on Late Nite with David Letterman
June 14 marks the 52nd anniversary of the recording of Paul McCartney’s “Yesterday,” the most covered song of the last half century.  If rock and roll had a human timeline, then perhaps you could think of the early days of Elvis and Little Richard as fevered adolescence and the 60s as a rebellious early adulthood. In that sense, “Yesterday” fits squarely between the two—youthful, philosophical, simple, but otherwise unassailable.  Love it or not, it's quite catchy with good words, good chords, and it's easy to remember.  Our only collective regret would be that it has been covered so much that it’s hard to hear "Yesterday" for what it is: a whistful ballad with a light touch.  Perhaps the best version if the Take 1, which features McCartney by himself, without the string quartet, with a brief introduction where McCartney tells George Harrison that he has tuned his guitar down a whole step so he can play the song--in the key of F-- as if he were playing in the key of G.
If you compare "Yesterday" with the early contemplative  and equally philosophical songs of Ray Davies and Pete Townshend, it doesn’t seem so out of place in the English pop music scene of 1965.  Like England itself, “Yesterday” is evergreen, slightly lush, betrays a slight discomfort on the part of the singer that he has to reveal a private longing. Though it might not be a true Lennon & McCartney composition, it was one of many Beatle songs released in 1965 that expressed the thought that growing up was complicated and a little looking back might not be a bad idea. Some of their other titles that year included “Help” “We Can Work It Out” and “In My Life”.  

It might not be everyone’s favorite Beatles song (including The Beatles themselves) but it has since been covered by a dizzying number of artists ("way too many," McCartney told Terry Gross on Fresh Air) including guitarist Al Caiola, Sam Cooke's childhood pal Lou Rawls, Perry Como, Johnny Mathis, Sarah Vaughan, Brenda Lee, Jerry Butler, Ace Cannon, Tom Jones, Ray Charles, and Vince Guaraldi. After "Yesterday", no one could claim The Beatles were only a silly little rock and roll band. For one thing, the members of that silly little rock and roll group were now rich and were as famous as Her Majesty herself. The new found freedom of having money and a home of their own (let alone a private room) helped to spark the song which began with the equally immortal title, "Scrambled Eggs." 

“I used to live in this little flat at the top of a house and I had a piano by the bed," McCartney recalled during the filming of The Beatles Anthology. "And I just woke up one morning with this tune in my head. I don’t know this tune...or do I? It’s like an old jazz tune or something—because my Dad used to know a lot of old jazz stuff. Maybe I’m just remembering it. So I went to the piano, found the chords. And I called it Scrambled Eggs…how I love your legs…so I wouldn’t forget it. I made sure I remembered it and hocked it around to all my friends. What is this? It’s got to be something. It’s like a good little tune but I couldn’t have written it---I just dreamed it! You don’t get that lucky.  I looked at them (The Beatles) and went oops…solo record. And they said, “yeah, it doesn’t matter. There’s nothing we could add to it so do it.”
Though there is no demo of “Yesterday” that exists, the Beatles were actively using reel to reel machines at home to make sketches before going to the studio.  “When we’re on our own and we have an idea for a song, the main thing is get it down so it’s not forgotten," John Lennon told The Beatles fan magazine in 1965.  "We’ve found the best way to do that is to use a tape recorder.”
The Beatles road manager and longest ally Neil Aspinall talked about McCartney’s process in 1966.  “Paul’s greatest hobby at the moment is tape recording. He has a room which is stacked with recording equipment. It’s loaded with special devices and Paul spends hours twiddling complicated sets of controls, a great big pair of headphones strapped to his ears. He’s become an expert at recording and double tracking…When Paul wanted to show Ringo how “What Goes On” sounded like, he made up a multi-track tape. Onto this went Paul singing, Paul playing lead guitar, Paul playing bass, and Paul playing drums. Then Ringo listened to the finished tape and added his own ideas before the recording session."
“Yesterday” was cut at Abbey Road on June 14, 1965, the week before Paul’s 23rd birthday.  Two live takes were made, just voice and Paul's new Epiphone Texan acoustic (George Harrison is heard off mic discussing Paul’s tuning which seems to be down a whole step so he can play in the key of F using “G” positions.)
“I told Paul that the only thing I could honestly think of to add to it would be strings, recalled George Martin in Recording the Beatles, “but Paul said, “Oh I don’t think I want Mantovani and Norrie Paramor very much…I suggested a small amount of strings, perhaps a classic string quartet.”
And so using Martin's arrangement, a string quartet was overdubbed the following week. It turned out to be the last day of recording for the soundtrack for Help. In England, “Yesterday” was never released as a single and appeared on the B-side of the LP, just before the closer, a burning cover of Larry Williams’ “Dizzy Miss Lizzie.” 

You could certainly lose more than a few precious days chasing down Beatle facts about "Yesterday" and there’s no shortage of fascinating (if you’re a Beatle fan) tidbits about the little song that took over the world, including an interview with John and Paul with Brian Matthews of the BBC, reproduced in Kevin Howlett’s The Beatles: The BBC Archives: 1962–1970.
Brian: "Give us the inside story on the song 'Yesterday.'"

John: "Ah well, this is John saying I don't know anything about that one. I'll hand you over to Paul."
Paul: " This is Paul, taking up the story in a holiday villa in Corsica, strumming away on a medieval guitar, I thought [sings] 'Scrambled Egg.' But I never could finish it, and eventually I took it back in. With the ancient wisdom of the east, John came out with [sings] 'Yesterday'."

How many times has McCartney sung "Yesterday" in concert? It's always on the set list.  (His fans demand it.) Whatever “Yesterday” may still mean to him now—or you—doesn't matter so much anymore.  You can count on McCartney to always give his fans their money’s worth.  McCartney never forgets he was once a young kid from Liverpool who just wanted to be a musician and that he was lucky to have once made good with his mates and also discovered one morning that he had dreamed a song that would last forever—along with the Epiphone guitar he used to record it. That's a fine accomplishment in itself and there's probably still a good version or two still to come from some clever youngster who couldn't care less about where the song came from, only what it might mean to him or her.

You can also count on cheeky Sir Paul leaving you with a surprise. On that June day in 1965, 22-year old pre-Sir-but-still-Fab Paul brought another new song to the studio, possibly to reassure his bandmates that he still wanted to play rock and roll---a catchy little tune called, “I’m Down.”