Sticking with Grahame's example, I plugged Salisbury to London Terminals into Advantix. The restriction UR has been modified since my copy of Advantix (checked on
www.nationalrail.co.uk/UR) to weekend-style restrictions for this new ticket. The change has obviously been planned for a while.
Going back to
SWT▸ 's assertion that you must upgrade a Super Off Peak ticket before you board if it is not valid on the service you intend to travel on (and then, in practical terms, potentially miss that service due to ticket office queues etc.) the
NRCOT▸ says:
9.2
If you are unable to present a valid Ticket when asked, we are permitted, in law,
to take one of the following measures:
a)
To charge you a Penalty Fare on certain trains and stations (see section 10
below); or
b)
To charge you the full undiscounted anytime single fare to a station directly
served by the train that you are on. You will not be entitled to any discounts
or special terms, or for a Ticket to a station other than one served by the train
that you are on; or
c)
To report you for prosecution.
If you are unable to present a valid Ticket or to pay a fare (including a part
payment of a Penalty Fare to the value of the Ticket required) when requested,
you will be required to provide your name and address so that the matter can be
followed up.
9.3
It is an offence under the Railway Byelaws to fail to provide your name and
address when requested
9.4
Notwithstanding Condition 9.2 (b) above, if you are using an advance Ticket and
you miss your booked train because a previous connecting train service was
delayed, you will be able to travel on the next train service provided by the Train
Company with whom you were booked without penalty.
If you have an ‘off-peak’ or ‘super off-peak’ Ticket, correctly dated but invalid for
the service on which you are travelling; you are using a route for which your
Ticket is not valid; or you break your journey when you are not permitted to do
so,
you will be charged the difference between the fare that you have paid and
the lowest price Ticket that is valid for the train you are using.