I regret that I haven't felt insipred to participate in this debate! One quick post and I was gone, but tony_mac, I had thought that my reference to "a person in control" of an item may have assisted (in addition to the "Owner") and my hints at legal Judgements on discarded items.
I hesitate to quote from myself, but it was "As the Railway Company has allowed the passenger to be in control of the ticket, and after the completion of its intended use (by both parties), and without any further request or action by the Railway Company, the passenger would be quite entitled to destroy it or to transfer it to someone else for destruction/ recycling etc (as long as it was not a Dishonest transfer)."
What follows from this? Well, the matter of dropping litter in the form of a Rail Ticket, is the liability of the passenger. (The person on control of the item).
The matter of retaining the ticket for future inspection or retention by a TOC must be proscribed by pragmatic considerations. 21st Century Consumer T&Cs would probably cover this in detail, but our aged CoC will just have to do, and they just manage. They do fail to define the expiry of the requirements after travel - specifically, the expiry of any claim to recover a ticket, though we are not completely in the dark.
The jurisdiction over the property (by the owner, BR and now TOCs) cannot be in perpetuity. The Judgement in Woodman entitled the owner (the TOCs in our case) to claim entitlement after some time, and I expect this is at the heart of your concern. However, I struggle to see how that matter (it concerned abandoned metals with an intrinsic market value) can be applied to a Rail Ticket, which is a mere token of a Permit to be conveyed within a specific period of time. That latter time constraint distinguishes an expired ticket from scrap metal adequately to refute Woodman in my opinion.
I can't find any Case Law which would re-assure you further tony_mac, but it is incredible that a claim of possession beyond the currency of the journeys permitted by the TOC could suceed in Law. I have a few lines of thought through comparable cases to support this, but none that directly answers your question, sorry.
However, I had hoped to re-assure with my reference to the wonderful Benjamin Pell. If my memory is correct, he made a respectable income from selling his stories of scandalous behaviour by wealthy people in the public eye, took the papers from the bins of wealthy Law Firms concerned to protect (alledged) wrong-doing by personalities and politicians, carried on taking the property of others (legal papers with no market face value) for years, and which cost the Personalities probably hundreds of thousands in damages, and was doing all this in the full gaze of the public, the police and presumably the injured parties; the point is that he was taking the property of someone else without their permission. He obtained a more-than-respectable income from his finds. Normally, this would be Theft to you and me.
And the high-profile Libel Law Firms (and their famous clients) thought so too. They wanted to claim that the contents of their back lane rubbish bins were still theirs (or their Clients'), and that Benjy was a Thief.
These cases againt Benjy illustrate that while the Law may be compelled to agree that these documents, and our Railway tickets, may still belong to another, we have two reasons to feel confident:
The TOC places the passenger in a postion of control of the property. Beyond the currency of the ticket, only an investigation into Fraud (or other serious Crime) could require the production of the ticket as evidence (It would be siezed under the provisions of PACE, and even PACE only allows the Police to retain the evidence until the Investigation and any subsequent proceedings are concluded).
When the Courts have been compelled to Judge against Benjy-the-Binman after the loss of perhaps as much as a million (I really have't a clue how much celebs and politicians might have 'lost') then they concluded the elaborate proceedings with a fine of just a tenner.
If we're still missing something in your question then lets give it one more go. Otherwise we really will have to draw a line.