Where did you get that from Jimmie? Must be out of date now as the "National Rail Conditions of Carriage" state:
"
15 Breaking or ending a journey at intermediate stations
You have the right to break and resume a journey covered by your ticket
(in either direction in the case of a return ticket) at any intermediate
station, as long as your ticket is valid for the trains you want to use. You
may also end your journey before the destination shown on your ticket at
any such intermediate station. However, these rights may not apply to
certain tickets. If so, the relevant Train Companies will state this in their
notices and other publications.
If you break or resume your journey when you are not entitled to do so,
you will be liable to pay the difference between the price of your ticket and
the price of the cheapest ticket(s) available for immediate travel that would
have entitled you to break or resume your journey on the service(s) you
have used.
If you end your journey at an intermediate station when you are not
entitled to do so, you will have to pay the difference between the price of
your ticket and the price of the cheapest ticket available for immediate
travel that would have entitled you to end your journey at that station on
the service you have used.
Please note that a ticket which entitles you to travel on the London
Underground does not entitle you to break and resume your journey at
any of its stations unless it is a season ticket or a Travelcard."
When you book on
www.nationalrail.co.uk, look at the ticket conditions and it will tell you if break of journey is allowed for that ticket.