Go to the co-ordinates and face the soldier. Use what you see to figure out the next co-ordinate.
The co-ordinate for the final cache is as follows
N 46 09.1AE
W 067 BC.ADC
A = The number of letters in the first name of Mr. E. Lynott = A
B= The number of letters in the name of the soldier on the bottom right, subtract 8 = B
C = The number of letter in the last name of the soldier on the left, third down.
D = The number on the statue "? Battle YPres"
E = the number of letters in the first name of Mr P Whalen, subtract 5 = E.
This will give you the co-ordinates for the final.
Sum Checker - 57