I left a camera over them on the off-chance that I would capture an image of whatever was responsible and although squirrel, badger and pine marten visited the log, none were observed feeding.
Visiting again this year I found many more fruiting bodies but so far, little evidence of feeding.
I checked the camera today for the first time and discovered that a roe deer had visited and sniffed at the fungi, but without feeding, a little over an hour before I arrived.
The camera is set to shoot a jpg file and then a thirty second video without a trigger delay. Left shows the deer heading to the log and two seconds later the video below shows it nosing at the fungi before moving away again.
Maybe the fungi are not quite right for eating yet or maybe its another animal responsible, but whichever, the camera will stay on site until I have an answer.