Hi, I'm no expert but pretty sure this is a partial racoon skull. If you compare the sticky-out features ( a scientist may be along to correct my 'technical' term ) at either side with those of a dog/possum/racoon the closest match I could find is the racoon.
If you put something that is internationally standard alongside in the photo, it gives folk an idea of the scale of the skull. Try not to avoid coins, a clearly marked ruler is ideal, bottle tops or soda cans work too.
I'm no expert sadly, and even less familiar with animals not found in the UK. Also there are no teeth preserved and these are usually the first things I look at to have a go. Racoon sounds sensible and you can see pictures of raccoon skulls on this great website http://1kai.dokkyomed.ac.jp/mammal/en/species/procyon_lotor.html