The Southern website claims, in a well-hidden section not made available or referenced at the point of purchase, that BoJ is forbidden on both legs of Super Off-Peak tickets:
https://www.southernrailway.com/tickets-and-fares/ticket-types/super-off-peak-tickets/
but the T & Cs available at the point of purchase effectively state that it is permitted, as does the NRE website, supposedly the 'definitive source of information'. To be more accurate, both the T & Cs and the NRE website state:
Outward:
A break of journey is permitted on the outward portion of an Super Off-Peak Day Return unless otherwise indicated by a restriction shown against the ticket's Restriction Code.
Return:
A break of journey is permitted on the return portion of an Super Off-Peak Day Return unless otherwise indicated by a restriction shown against the ticket's Restriction Code.
Since no such restriction exists in restriction code PB, it is permitted on both legs:
http://www.nationalrail.co.uk/PB).
(There is a prohibition on BoJ listed in brfares.com for this type of Super Off Peak Day Return (PDR), but this is not an official source of information and does not form part of the contract for travel).
It is easy for a 'normal' passenger acting in good faith to buy such a ticket from the Southern booking engine, without having seen or been made aware of the supposed prohibition, and to reasonably believe based on the information at the point of purchase that it is permitted, such that they then choose to enter into the contract for travel on the basis that it is declared to be permitted.
Similiar considerations apply to VTEC's half-price SSS, where the T & Cs purporting to forbid BoJ are well hidden on their website, and the T & Cs available at the point of purchase state that it is permitted unless forbidden by the restriction code, and, again, no such restriction exists.
As a further example, the published T & Cs on the SWT website relating to their promotional £20 ticket are silent on BoJ save to note that the NRCoC applies, and TVMs selling this ticket make no mention of any restriction; however, the information box at the point of online purchase claims that it is prohibited.
The NRCoC states:
[extract from 'Your Rights']
You can:
• Start, break or resume your journey using trains on which your ticket is valid unless you are told about particular restrictions that apply to the use of your ticket.
[extract from Condition 16]
However, these rights may not apply to
some types of tickets for which a break of journey is prohibited, in which case the Ticket Seller must make this clear when you buy your ticket.
It follows that conflicting or hidden information, not easily accessible at the point of purchase, cannot be said to satisfy the NRCoC requirement that the restrictions be "made clear", and cannot be said to form part of the contract for travel; hence the contract for travel is subject to the 'default' rule for flexible tickets in the NRCoC that BoJ is permitted.