See 'GC5PR6Z #1 Mitford March - I Spy' for series details You will need to have completed certain parts of the Mitford March series to gather the required information to calculate the coords for this final stage. It's a large container so where could it be?
It can be found at N 55 10.a W 001 43.b where
a = 156 + X - Y - Z
b = 846 - X + Y + Z
Well done to Monteluce and SpeedyGC on FTF
You can validate your puzzle solution with certitude.
Lbh ner ybbxvat sbe n fgnaqneq fvmr nzzb pna.
Vg vf ba gur tebhaq haqre n ynetr ovg bs pnzb. Irel arne n irel ebggra snyyra gerr gehax.