(22 Sep 2013, 6:00 pm)Michael wrote Could the 13/14 not run from a different depot? not sure of its locations as i'm not from the area.
3 suggestions for 13/14 :-
Interwork with 15/15A at Durham,
or interwork with X25 at Langley Park,
or run it as a through service at Durham with 20/20A.
X25 would be best, with Fri/Sat evening and Sunday buses interworked at Durham with 21.