Without writing a book on the subject you can summarise roughly, and I say roughly since there is never any golden rule that applies to something like this and there have always been people willing to take a shortcut to try and gain short term dancefloor popularity. There are also regional differences. For example in London there has always been a seemingly endless supply of people setting up soul do's and playing boots:
-1960's
Music largely played on UK release a few imports, increasing as the decade went on.
- Early 1970's -
Loads of imports on OV. Loads of new discoveries coming through from Soul Bowl, Levine, SS, and a host of others. Still some UK releases. Probably some early boots played at soul nights,
- Mid 70s "WIgan explosion" -
Niters / Dayers playing OV + EMIdiscs (purpose made acetate copies like Carvers today) of "in demanders".
Soul Nights depending on where you were playing either OV, Boots or a mix.
Think a few boots played by what I'd class as "2nd division Wigan DJs" (the fillers rather than the main "names").
- Post Wigan / Stafford / 100 Club etc.
OV still rules at Niters / Dayers.
Mod revival nights / weekends loads of boots / reissues etc.
Today:
Well you know the answer to that....