WHO WAS A.J.B?

I was stopped in my tracks during a walk near South Brent, Devon, the other day by the sight of this little cross and the poignant words nearby. Who was 'A.J.B - Royal Navy' and how was he 'taken by this tree' in 1990?

Did the tree fall and kill him, or did he die naturally at that spot? Whoever he was, someone still marks with fresh flowers the place where he died, keeping his memory alive.