Why would anyone hide a nano in the woods?
Well sometimes it is just for a difficult cache. This may be really tough or very easy. I really am uncertain. But you won't know unless yew go.
At the initial coordinates you will find a year. Let this be ABCD
Then the final location is at N 51 ((C-D)*B).(((C-D)*B)+(D-A)) W 000 (A+B).((B+C)*C)-A
Permission has been given by the warden for Mitcham Common.
You can validate your puzzle solution with certitude.