It should also be noted that a return ticket is valid for the return anytime within 5 days.
I also heard a driver tell a passenger their ticket could be used for two journeys in the same direction within those 5 days. The example was passenger gets bus from A to B, gets a lift home from a friend from B to A, they could then use the return leg for another A to B journey, rather than being restricted to using the return leg from B to A. I can't find any literature confirming that to be correct though.
Believe not correct rw. The A-B leg has been used. The B-A leg is unused and will be valid for 5 days (from date of issue) in that direction only.