Badfinger did the sound track for the movie "The Magic Christian", and they sang that song, but McCartney wrote it...

Track 1:Come And Get It (Paul McCartney)

This fabulous song was recorded in Studio 2, at Abbey Road Studios on July 24, 1969, during the Abbey Road Sessions. With Paul at lead vocal, it was recorded the same day as "Sun King." Unreleased commercially by The Beatles, it was given to the band Badfinger, who recorded it and which became their first hit in 1970. This song by Badfinger was also featured in the movie, "The Magic Christian," which starred Peter Sellers and Ringo Starr.

http://www.iamthebeatles.com/article1045.html

On the subject of The Magic Christian, I loved the book and hated the movie. And the song that goes with it.