Stage 1 - Windmill
Goto N52°36.243 & W002°33.314. To enjoy views of the windmill
Stage 2 - Ammo Box Location
Goto N52' 36.501 W002' 33.825
The cache is an ammo box, containing the usual assortment of goodies.
Extras !
Look in the log book for details of the BONUS CACHE - GC18HRW, hidden nearby (you will need to return to the car and drive to this location)