The worst case scenario here could be that Bulmer persuaded those around him, the people who received the material after he died, that it was of little value and that there was little money to be made from it but a lot of hassle involved in putting it out. That might have been his own thinking as he sat on the material for all those years. So if the stuff still actually exists, whoever has it now might not be looking after it very well and it might be stuffed away somewhere, long-forgotten. It's been so long now that one might feel that it's permitted to feel gloomy about it. Anyone out there with pristine vinyl, keep looking after it! One day...?