Welcome to the forum, Mate. Yes, as
Kawa says, this is quite an interesting one. My own hunch is that it's something to do with the HME (which I would remove myself, as I say). But this is one of those problems that it's difficult to get to grips with without a diagram, photo ... or better still, actually
being there! I guess we now await news from Kev (with, as it were, baited breath)!

PS: Devon, Dorset ... or good old
Somerset?