I don't believe there is, at least nothing official. In the early post-11th September period, there were a number of issues with enthusiasts being reported for "suspicious" behaviour and so on. Rules were introduced about getting permission before photography trips on stations, and these days most TOCs are fairly fair-minded when it comes to enthusiasts.Basically you join a scheme where by you agree to report anything suspicious to police and it was a joint thing between airport authority and police where by registering details and providing passport sized photos you where issued with an ID card that showed you was part of the scheme and a genuine enthusiast so if you where near an airport and someone asked what you was doing you could explain and show the card.
The point being that not only would it prove what you was doing but it helps to build relationships between the enthusiast and authorities.
Is there any schemes like this for the railway and enthusiasts?
As the hobby has diversified over the years we now have : -It was called "The Ian Allan Locospotters' Club"
I carry a copy of that webpage when I'm photting at a station, so that when some jobsworth tells me it's illegal to take photos I can inform him of his ignorance.