Here is a bit of info about some rare items which I know exist in record companies archives.
Maybe one day we will be lucky and some of them will be released.
My Baby (unreleased track) - single sided acetates
3 December 1968
Demo Tape with 2 unreleased tracks: You Still Live Here / Real Emotion
River To Another Day (different versions to released track) - single sided acetates
Twangin' acetate - features unreleased track Swingin Doors and also a different version of Baby Ride Easy to the released track
London's A Lonely Town acetate - ok this is not so rare as a track as it was released but it is still a great item