Unlike your till receipts a train ticket appears to be the 'property of the railways' in perpetuity. Does this mean that technically, possession of train tickets after the journey has been made is tantamount to theft ?
Of course not!
As others have said, 'theft' requires the Dishonesty of the person taking the property and Section 2 of the Theft Act provides some help in defining instances where Dishonesty is NOT to be assumed (e.g. "if he appropriates the property in the belief that he would have the other’s consent "); this requires some demonstration that the previous owner is unwilling for posession to be passed to the subsequent person (usually they simply demonstrate that lack of intention by simply seeking the return of the property!).
But the ownership of discarded property can be quite unclear. In England & Wales, it is hard to give up ownership of something as long as someone can be said to be in control of the item(s), [Woodman (1974)]. Even property left in the street in a bin bag for collection bythe Local Authority is still the property, or is in the control of, the owner, until it is physically picked up by that collection as intended by the owner (or person in control).
In Scotland, discarded property can and does effectively become the State's responsibility (The Theft Act applies but so does Scots Common Law!).
The ownership of the ticket remains with the Railway in perpetuity and technically it could ask for it back at any time in the future.
Until, that is, the legal owner in the form of a Railway Company in England or Wales transfers it to a recycling/ waste/ shredding contractor or authority or other persons.
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).
The Courts have not been very sympathetic to claims of theft of (apparently) discarded property. The notorious Benjamin Pell collected thousands of documents from the bins of London Law firms and laid them out to dry in the front garden for every passing commuter to see and he did so for years on end. The more scandalous of these documents were sold to the press for a handsome price and led to a variety of revelations involving popular and important people resulting in huge claims of libel; eventually he was prosecuted and fined, IIRC, £10.
