I've attended a handful of the maestro's promotional interviews for his memoirs and at the most recent one on Thursday he revealed that "Mainstream" will get a reissue in the new year to mark its half century.
Better still, he told us that the release will contain a handful of new recordings by the original band members! This came as a welcome surprise, as Bill MacCormick laid down his bass several years ago (due to arthritis, I believe) and keyboardist Dave Jarrett was thought to have disappeared into the world of academia.
Should be interesting!