Is "John" Our Paul's Real First Name?

In my April 22, 2013 post, I speculated that our Paul's real name might be David Black.  But I thought back to my Beatle fan days beginning in 1964 and how in Detroit we heard that Paul's real first name was JOHN and that he used his middle name, Paul:  1,) to not confuse fans with two Johns in the group; and 2.) because, John, being the founder of the group, should be the one to use his own first name.

Interesting . . . especially when the later claim was that Paul's first name was JAMES, (named after his father), and that the official recording of his first name is listed as JAMES.

In the first two editions of the book, The Beatles:  The Authorized Biography by Hunter Davies, Paul's first name is listed as JOHN.  Both editions (1968 and 1978) were, of course, published after our Paul was--I believe-- removed from the group.

But that detail  I heard as a kid Beatles fan coupled with the information from the book strongly suggest that our Paul's real first name was JOHN.