Thank you for the invaluable tips. I have been trawling through the footage from last July/August and any photos that I could find. In the colour photos she has a dark line at the top of the skirt and then it turns very pale, much paler than her spines, she also has the dark feet that you pointed out with much paler fur on her legs and this can be seen in both the footage from last year and the two clips from the other night. Also her dark ears only show up from the side and not the front. I am as convinced as I can be that it is Fern. I found her in some later clips up to the 19th of August last year. In the last three days of footage, before her disappearance, she had been given a paint job in the form of a large stripe on one side, so somebody else was obviously keeping an eye on her. At the same time, we had a lot of young hogs visiting, far more than the adults, so I had cut right back on the mealworms to just half a dozen on the top as a garnish. I suppose it’s possible that Fern took the hump and decided to dine at her paint and decorator’s where the mealworms may have been more freely available!
So far this year, I have still only seen two youngsters, but there are lots of adults. In comparison, this time last year there were lots of juveniles, too many to count and hardly any adults….not quite sure what’s going on there!