Have a look at the Beatles photo at http://www.wolfgangsvault.com -- it's of the group arriving in San Francisco in 1966 for their final U.S. concert. (Click on it to see full-screen -- and look at the other great stuff on this site from impresario Bill Graham's collections.)
What camera do you think Paul is holding? Not a Spotmatic, I don't think, so I'd go with a Nikon F due to the shutter speed dial size and what I can see of the film advance lever. I guess Paul would have seen enough Nikon F's in the hand of myriad photographers that he'd gravitate in that direction.