At last Graham I've traced the culprit raiding the runners, caught on it's way to the crime scene not the Giant Slug but the below

Yes the common all garden snail.
Not good on moths but is this a Hedge Rustic. It came indoors when the lights were on.
Finally caught this last pic on a walk searching for insects along Skinners Wall, Manningtree. No Insects but plenty of Egrets which led to this dispute over fishing rights

Yes the common all garden snail.
Not good on moths but is this a Hedge Rustic. It came indoors when the lights were on.

Finally caught this last pic on a walk searching for insects along Skinners Wall, Manningtree. No Insects but plenty of Egrets which led to this dispute over fishing rights