I think there is a greater awareness of split ticketing these days. Although it was a former BR member of staff at my local ticket office who introduced me to the concept as he saw the journey I was making would be cheaper with 2 tickets. I find on train staff are not likely to question it now, where as before you could see it was something they were not used to, they might say "oh are you staying on after [name of station], but never refused to accept the ticket.
Under what circumstances can a ticket office refuse to sell a ticket?
I really do hope that the TOCs do not try to ban split ticketing, like in Ireland. I would like to think that this would be very difficult (hopefully impossible) for them to do. I would hate a situation whereby you were having to get off the train at every station you wanted to change from one ticket to another (and possibly have to exit the station and walk back in). Someone tell me this would be be very hard for them to do... I cannot see any valid reason for them banning it, other then the fact they are not wanting passengers to pay less.
"Not entirely true, there are times that sales can be refused, however, split ticketing should not be a reason to refuse sale."
"However, if a customer specifically asks for a particular combination of tickets you must sell those tickets, as long as your office has the necessary fares manuals, ticket issuing system and/or reservation facilities to do so."
Would it be fair to say that now a days even the most small of ticket offices would have the facilities to issue any ticket asked for, and therefore could do a split ticket no problem? I say this because all ticket offices now are computerised surely using the one central system containing all rail fares? (its years since I've seen a fares manual being used behind a booking office window)