A mate of mine had the same problem in france years ago…he was parked in a layby…someone ran into the back of him whilst he was asleep…he got arrested…dont know why…nor did he…but released once they had done tests on the body…and realised he was well over the limit.
What with parking in a layby overnight…there is the risk also of a very large fine in kent for doing so. r.i.p. to the guys in the merc.