I don't know how old you are PFR but yes the bulk of the stuff Dave bought the ownership and copyright for was "reputedly worthy deleted LPs". I think most people who had a serious interest in folk music at the time the material was produced were more than likely aware it was there - in a lot of cases they would not have the sort of disposable income the current generation enjoys. There was at the time a fair chance a lot of the stuff would have ended up in a skip!

So maybe Dave didn't live long enough!