The station site at Salcey has always been of fascination to me for an age. I think I’ve been there, well very close by… now I’m not sure prior to hijacking a thread by Alan, I am re-opening the conversation here on a new one.
The above link takes you to where I thought the station site was. I have emailed the owner of the images. Have you any more info to add?
When I visited the site in 2011 a farmer did inform me that it was not a public footpath. He wasn't aggresive nor did he tell me to get off. Afterwards I thought that perhaps he didn't own the land but used it as an unofficial track to get around his farm. Anyway, I'm pretty sure if you park your car on the road, past Piddington village, he will see it and come investigating!
Don't worry about getting into trouble, the farmer from Church Farm in Piddington uses the trackbed to drive his tractor, mainly during the spring and summer, albeit unoften. It's a pretty desolate place at the best of times, so you'd be fine. I was fine walking through between the A508 and Roade Curve, which is far more public.