it depends on the ticket type...
say for example SDS (standard day single) it permits a break of journey but the journey must be completed in the day. a SOS (standard open single) also permits a break of journey but you have five days to complete it in.
some tickets allow overnight break even if the expirey date is the previous day, these are usually associated with journies which physically can not be made within the day...
I shall post EXACTLY what it says in the TEH (ticket examiners handbook) issued only a few months ago, when i get back from my travels.
Ticket is out of date, then tough luck you'll need to buy another one!
Queue the posts stating that i am wrong, poorly trained and that the TEH is wrong and they are right... :roll::roll:
An SOS is valid for 2 days (a slip of the keyboard there I assume).
However, as things stand, an Off-Peak ticket
does allow travel into the second day if the journey 'cannot' be completed on the first day, the nature of the rule meaning that
it is down to the customer to decide. Such a rule is frankly ridiculous for a journey from Sheffield to York but as the same off-peak ticket type is used on that journey as for a journey from, say, Plymouth to Aberdeen, the same rules have to apply.
There is a piece of work in progress to split longer and shorter distance off-peak tickets into two ticket types. Once that has happened, we can move to a far more sensible arrangement in which the shorter distances will only be valid for one day, and the longer ones will be valid for two days, and it will state clearly on the ticket which applies.
Until then, the rule remains that for an Off-Peak return the journey must commence on the first day, but if it cannot be completed you can finish the journey the following day. The definition of 'cannot be completed' needs to be left to the customer because the definition of which ones cannot be completed depends on so many outside factors, e.g. actual distance; the time that travel commenced; the route being taken; whether there is engineering work or disruption; the need for a passenger actually to stop somewhere they can spend the night; and so on.
Many of the users of this site are very eagle eyed and will happily exploit a rule for a purpose that isn't intended - and, lets face it, anyone going from, say, Rugby to London who claims they cannot complete the journey and must spend the night in Milton Keynes is definitely exploiting this rule in a way that is not the intention. But in that regard, it is no different to split tickets, permitted routes, etc etc. If you know the rules and use them to the letter, it is allowed...!