Marc,
great write up. thanks for sharing.
Mel Jackson picture cover rings a bell, think a mate played it to me a long time ago. But I don't recall it as being good, you're sure you're not mixing it up with Marv Williams - Goodbye my love? Because that's a lovely funky track, sadly a bit too fast for the dancefloor IMO.
Kerston Records started in 1965 so 1967 for John Harris makes more sense.