Steve-O ,
" Stolen" was enough to cause a court case over it - I believe in the US .
The story is something like this, that, Paul Simon recorded the song believing it to be something like (say) Greensleeves - which is so old it has no copyright / is traditional.
Scarborough Fair became very popular not least for appearing repeatedly in the film the Graduate   
Martin had found a poem in a old book - he put the tune to the words and the arrangement of the words and song. This type of thing was part of the Revivalist movement in the 50's and 60's and an important step to getting the Folk music movement off it's knees.
The matter was settled out of court , the amounts and whether satisfaction was achieved is not for me to comment on only that   " baloney " is out of place when discusing this particular Song and matter.