A few years ago, before I retired from the rail industry, I compiled a list of stations that are on private land. I don't have access to that document any more but I reckon that there were 50 or more around the national rail network, with varying degrees of permissive public access for pedestrians and/or vehicles.
Somewhere in the south of England there is a station where the building is now an office, but the owners of the office try to prevent passengers being dropped off/picked up by car. The legality of the company's notices on the access road is somewhat suspect, and is ripe for being challenged. Similar situation to Altnabraeic I think, in that what they really own and what they claim to own may differ.