P[{q[i_,j_],q[k_,l_]}]:=Abs[j-l]!=Abs[i-k]; fortytwo[N_]:=Select[Inner[q,Range[N],#,List]&/@Permutations[Range[N]],Function[q,And@@(P/@(Flatten[Table[{q[[n]],q[[m]]},{n,1,Length[q]},{m,n+1,Length[q]}],1]))]];
You know the answer, but what is the question? Once you know it, you will know N, and who it is all about. Convert the letters of the latter into numbers (A=1, B=2, ...) to get A,B,C,D,E,F and their crossfeet a,b,c,d,e,f. Find the cache at:
N48° (N-a)(C-b).(D)(f-b)(B-E)
E16° (e-b)(E-N).(E-f)(F-A+2)(F-D-N-c)
For a crosscheck of your solution, add all the crossfeet a-f and N - if your result is not exactly two more than the answer to everything, then try again!
IMPORTANT NOTE: once you have the coordinates, it is not straight-forward how to access the cache without trepassing private property. Nagaro checked that there is still a legally accepted way to approach the cache, but as a detailled description would be a spoiler, I will give this description only by private and confidential email to those who contact me with their correct solution. Of course you are always free to try it all by yourself, but be careful not to trespass!
You can check your answers for this puzzle on Geochecker.com.
...the listing above is the original version from frigschneck.
Additional Notes: Currently there are no fences anymore; the area is now accessible for the general public.