Played on my AR80 organ. The advantage of an organ over a keyboard is that you have two manuals (an 'upper' and a 'lower') and these can be set to two different Voices. Then while you are playing you can 'jump' from one manual to the other to get a 'counter melody' playing with a completely different sound.
Of course when you have an orchestra backing you the possibility of adding extra 'bits' into the music are endless. This is what I love about 60s music. The little counter-melodies that they add in right through the song make the song sound 'complete' somehow. If they weren't there you'd miss them.
"True Love Ways" Buddy Holly
Hugh