The above co-ordinates are for the TV mast on Dartmoor which is visible from the bonus cache.
To find this cache you first have to visit Dartmoor Ten Tors 1-10 in order to get the ten bonus digits. When you have all the digits the bonus cache can be found at N50º(C-B)(J-A).(F+H)(9-H)(I+A) W003º(D-2)(H+I).(G-I)(9+F-G)(A+B).
The cache is a pill pot with small swaps.
Terrain rating is for a combination of finding all caches. It drops to 3.3 when you know the final co-ordinates.
PLEASE DO NOT PUT ANY HINT/CLUE/SPOILER/PIC OF THE FINAL LOCATION ON YOUR LOG. I WILL DELETE WITHOUT NOTICE ANY LOG WHICH I FEEL FALLS INTO THIS CATEGORY.