The cache isn't at the published coordinates. You may find them a useful parking spot next to the old, long-closed Railway Swan public house.
The Bedford to Northampton Line was a branch of the Midland Railway which served stations in three counties: Northampton and Horton in Northamptonshire; Olney in Buckinghamshire; Turvey and Bedford in Bedfordshire. The trackbed was used by the Stevington & Turvey Light Railway till Summer 2014. Some photos can be found at https://www.flickr.com/photos/crowquine/sets/72157645542592774/
Very little now remains, though some track, signals and a lever frame are still in situ. Even the buffers the original cache was located on have been removed - within a couple of weeks of placing the cache! And the firstreplacement cache is in a tree behind the new fence!
Turvey has had some 'dodgy' railway events. A freight train collided with some empty coaching stock in 1960. Fortunately, there were no fatalities - other than the LMS Stannier 8F which was withdrawn from service soon after the accident. AB is the date; CD is the month; EFGHJ is the locomotive that was derailed down the embankment.
The cache is atNorth 52 C(H*9).G(F-H-A)(E-1) West CCC 3(D-1).(J-1)BF
The cache is now a small (approx 300ml) pot.
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Congratulations to dirtycourgette on being First To Find.