The given coordinates take you to a notice board. To find the physical cache you need to answer the following questions to calculate the coordinates.
How many words are there on the top of the notice board? A
How many letters are there in the 2nd word? B
How many letters in the 3rd word? C
The cache can be found at N51 42. A(B+1)(C+A-1) W002 54.CC (B-1)
As you walk to the final cache location from the notice board before bearing left look to the right and you will see the old tunnel. There is a footpath through the tunnel but you don't go that way to the cache. You may want to afterwards as there is a nature walk the other end and some kids like the spookiness. As you walk along the footpath to the cache if you look to right you will see the site of the former station, platforms and track. The path can get a little wet and muddy at times. Beware of dog muggles as this is a popular walk. You might also see me as I often walk this way.