When I went back to check on the enormous slime mould from earlier this month, a large sphere of spore mass had fallen off the log and landed on the forest floor. A dor beetle had found it, and seemed happily engrossed in rolling it around the leaf litter.
Photo3 was the spore mass before the fall. When I examined the spore mass under a microscope, it became clear that this is not Brefeldia maxima, but matched the description of another slime mould - Symphytocarpus amaurochaetoides except for the maximimum size - S. amaurochaetoides is supposed to max out at 5cm diameter, while my one was something like 40cm x 12cm.