As Lonnie was originally a banjo and guitar player with jazz bands like Ken Colyer's and Chris Barber's, it would be very normal for him to play the song in a key like F. In my years in a mainstream jazz band, most of the repertoire we played was in the keys of Bb, Eb and Ab, plus the relative minors of those keys. In reality, if you play (for example) Sweet Georgia Brown in F, most of the passing chords are quite easy changes - D7, G7, C7, etc.