Did Paul McCarthy play a fretless bass on abbey rd. ?
I've never heard of paul ever playing a fretless but some of the slides he does sound too smooth for a fretted bass. Especially on come together and bathroom window, then there's that tone. I know he owned hofner, fender and ric basses at the time, none of which made fretless basses at the time. But he was a pretty resourceful guy. His first bass was just a cheap guitar strung with piano wire, is it possible that he just ripped the frets off of one of his axes?
Just remember 99% of people are complete morons 99% of the time, but once in a great while they will totally throw you for a loop and do something smart...