[dr_lew]

I'm guessing it happened here, where the A381 enters the trees going uphill from left to right. Halwell to Harbetonford isn't a very long stretch, and this looks to me like it must be the place.

[Stoat]

Since I posted this thread, the Daily Mail has updated their posted article with a map of the accident location, and it appears that you’re exactly correct.

A new photo and an embedded YouTube video of one of their early songs “Ma Ma Ma Belle” has been added as well.