No interactions present.
Ukleps is an outstanding resource for moth larvae images and their identifications:-
This is a big geometridae caterpillar something like a willow beauty/ mottled beauty/ engrailed, just suggestions to begin looking. I would suggest a larger geometrid but some of them look quite alike as larva and require close inspection of the images to reach an ID.
Edit- just looked again, its really big, must be one of the largest geometrids in Britain.
I think you have it, if its not it its extremely like it. Just found something very similar tonight but only 4.5cm, the above one is much larger. I think this is the same species, post soon.
Igrange great post above.
Edit, just posted the one I found this evening here:
Lat/Lng: 51.7095, -1.995
OS grid ref: SP004011