I think this is either the Yellow Slug (L.flavus) or the Irish Yellow Slug (L.maculatus)...
No interactions present.
large pale green blotches
on a variable but mostly khaki background;
no pale ridge at keel
fine yellow speckles;
pale stripe along the keel (faint ridge down the middle of the back)
Thanks Martin, I have added it as an id.
Lat/Lng: 51.373, -2.3555
OS grid ref: ST753638