You are looking for the Red Post Box, the street it is on and will need to know the name of the nearby church.
The post box should have a Reference code visible on the front. NG _ _ _ _ _
The cache can be found at N52 5A.BCD W001 0E.FGH
A = the sum of the first 2 numbers in the reference code
B = the total number of numerical digits in the reference code
C = the first, third and fourth numerical digit all added. And then squared
D = the number of letters in the reference code.
E = how many churches, in Owthorpe, dedicated to Male Saints.
F = how many syllables in the street name where the post box is found (not including the word street)
G = number of letters in the village name -1
H = the number of times the letter z appears in the church name.
Village Signs Series If anybody would like to expand this series please do. I would just ask that you let Smokeypugs know first so they can keep track of the Village Sign numbers and names to avoid duplication.