. Not sure about Darlo though - Bishop instead?Sunderland - Dalton Park (I'd suggest via A690, Dox Park, A19) - Murton, Easington Lane, Haswell, Wingate, Quarrington Hill, Coxhoe, Spennymoor - current X21 route to Bishop. Bit of a dogs hind leg, but not certain of best/most populous route to Bishop from Dalton Park
Would make more sense when there is a prescence in the town already.