The owners of land (such as railway property) can decide whatever they like about whether to permit photography on their premises or not, but how they enforce that is a matter of conjecture - they do not have the right to confiscate cameras or insist that you delete any images! They can instigate action for trespass against the offender and remove them from the premises using reasonable force, and could take legal action in the courts but it would be debatable as to whether this would succeed.

This is a useful reference:-
http://www.sirimo.co.uk/wp-content/u...srights-v2.pdf

If you can take photos of trains at train stations, which I have done and in the presence of British Transport Police, many times then I do not see any issue taking pics of buses and trucks etc. Network Rail say that photos can be taken at stations as long as flash is not used, tripods don't get in the way of passengers and that the photos are not offered for sale.

I really do not see what harm is being done by enthusiasts photographing transport. No real difference to taking a picture of the Houses of Parliament and a London bus goes by - the result is still the same!