What happens if I buy a return from A to B at, say 10:00 in the morning, coming back about 19:00? If I turned up at A at this time and asked for 'a return to B' I would presumably be sold an off-peak return. However, if I was to break my journey on the outward leg at C would I be restricted in which trains I could use later from C to B if I were to do this during the peak?