Wow, this is a really hard call. IF the "old pocket book" is older then 1963 and there is some proof of the story being told, I would say that there is a good chance it is genuine as it does match well with known examples from that time. That being said, the secretarial signature from that time looked a lot like his real so you can never be 100 percent certain.
1963 is when the Beatles started to use secretarial.

1963 authentic
[img]http://i55.tinypic.com/1zv495s.jpg[/img]

1963 authentic
[img]http://i51.tinypic.com/rrowu0.jpg[/img]

1963 secretarial
[img]http://i54.tinypic.com/2zgdksm.jpg[/img]

Looks like his sig from years and years ago.
I would say its good, but beware, there are too many forgeries going round from Macca to be 100% sure.

[img]http://i10.photobucket.com/albums/a140/kornflakes11/Autographs/Paul.jpg[/img]

"This autograph was obtained at a concert where the Beatles were performing by my grandfather on the May 17th 1963 at the Grosvenor rooms in Norwich.

The signature was signed by Paul in Black pen on an old pocket book.The signature has faded over time and has some slight pen smudges but still displays great considering its age.I have taken a close up photo of the autograph so that you can see that its 100% authentic guaranteed."

What do you guys think? The bidding started incredibly low, but I'm sure the price will go way up if it is determined to be real. I am willing to spend a fair amount of money on a McCartney auto, but I am so paranoid about getting a fake.

All comments are appreciated!