The 110th in a series of caches where a red telephone box is in close proximity to a post box.
The only rule is that they have to be able to be photographed together, and the phone boxes have to be red.
To find the cache you will need to find out the postbox number - bottom left corner of the post box. Assume these numbers are DLvw xyzD.
The cache is at N54 42.(v+w)(x+y+z)(w+z-v-x-y) W001 35.(v+x+y+z)(z/2)(v+w+y)
The checksum of the 6 digits is 44