The cache is not at the headline co-ordinates, but a short walk away. You are looking for a 35mm film canister, but the log is inside an inner tube and tweezers may be useful.
To locate, take the number of the phone box, this is 01273 ABCDEF
Then check the postbox number, this BN6 GHJ
The cache is located at N50º 55.(G+J-H)BC W000º 06.F(D+G-E)A
The Fine Pair series was originally started by wizardsmum but is now managed by mattd2k.
If anybody would like to place 'A Fine Pair' of their own please do. I would just ask that you first visit www.afinepair.co.uk to request a number to avoid any duplication.
mattd2k also keeps a public Bookmark List of this series. Once your cache is published please contact him via at email@example.com to have yours added.