The cache is not at the posted coordinates but it is nearby.
There you will see a road sign. To where does the B183 go?
Add that place to the grid and then insert the numerical value of each letter where A=1 B=2 .... etc.
The cache is found at: N54 45.(F-C)(C-A)(G-H) W6 26.G(D-H)(I-D)
You and your geo-hounds may enjoy the opportunity to stretch your legs!