First off what an absolutely beautiful game. One of the most realistically rendered worlds I've seen yet. I live on an island at the other end of Britain to where this is set and I have to say that the coastline in parts could have been lifted straight from my home.
So, we know that this is set Britain, a Hebridean island to be precise. We hear about a road accident on the M5, we're told it is somewhere outside Wolverhampton. Later we are taken to a flashback of the accident. The signs lining the road are English road signs, the narrater constantly tells us the geographic location.
The game could not be more clear that we are in England during this flashback.
... are all the bloody cars left hand drive!?