The posted coordinates take you to a commemorative stone with two plaques. The final location is a short walk away at N52 ab.cde W001 fg.hjk. Stealth is required. To find the final coordinates the following information from the plaques is required.
Upper plaque, commemorating the twinning of the town
a = letters in month +1
b = anniversary years commemorated/2
c = last digit of year -1
d = letters in 5th line
e = number of times the letter A appears on this plaque
Lower plaque, giving a history of the site
f = last digit of 1st date
g = third digit of 2nd date -2
h = last digit of 3rd date +1
j = last digit of 2nd date
k = 2nd digit of the number of colour combinations
*Congratulations to Team-Triplet and PlasmaWave on FTF*