I continue to wonder why it is that 19(c) was written in such a vague way so as to be open to interpretation in the manner UK law tends to be?
So we presently have:
19. Using a combination of tickets
You may use two or more tickets for one journey as long as together they cover the entire
journey and one of the following applies:
(a) they are both Zonal Tickets unless special conditions prohibit their use in this
way. The Ticket Seller will, if you ask, advise you whether you can use a Zonal
Ticket in combination with another ticket.
(b) the train you are in calls at a station where you change from one ticket to another;
or
(c) one of the tickets is a Season Ticket (which for this purpose does not include
Season Tickets or travel passes issued on behalf of a passenger transport
executive or local authority) or a leisure travel pass, and the other ticket(s) is/
are not.
Would it not be better as something like the following (depending on the intentions - this is based on my view of what the intentions are):-
19. Using a combination of tickets
You may use two or more tickets for one journey as long as together they cover the entire journey, they have at least one station in common via (one of) which your journey must travel, and one or more of the following applies for each join between two tickets:
(a) They are both Rover or Ranger tickets, or Passenger Transport Executive, local authority or other tickets providing unlimited travel within a defined area, where there are no specific terms and conditions prohibiting such use.
(b) One ticket is a London Travelcard, and the other is a ticket from a relevant Boundary Zone. In this case, subject to any additional restrictions on the ticket, you may use any Permitted Route from the boundary of that Zone to/from the origin/destination on that ticket and need not pass through any specific station.
(c) The train you travel on calls at a station in common between the tickets as noted above for both joining and alighting.
(d) One ticket is a Season Ticket (which for this purpose does not include a season ticket issued for or on behalf of a local authority, Passenger Transport Executive or equivalent[1]) and the other is not. This is to allow the extension of a Season Ticket either using a single/return ticket or a ticket in note [1] provided the terms and conditions of that ticket in note [1] do not prohibit such use.
(e) One ticket is a Rover or Ranger ticket, and another ticket is being combined with it to travel into or out of the area of validity, provided the terms and conditions of both tickets do not prohibit such use.
Is that maybe better?