Bongo Jazz has a post about Aretha Franklin and ends with a video of Aretha and Ray Johnson performing “Mockingbird” on March 10, 1965. The arrangement is pretty similar to how James and Carly performed it, except the male vocal doesn’t take the lead in the second half and of course James’ added lyrics aren’t there. Still an interesting look at what could’ve inspired their arrangement.
For comparison’s sake, here’s James and Carly performing “Mockingbird” on the No Nukes movie from 1979.
And here’s the original version by Charlie & Inez Foxx from 1963: