(01 Sep 2016, 7:04 pm)South Tyne Lad wrote I'd take a guess in thinking if the 21 receives Streetdecks then Sunday X21s will move to Crook, As no fuel saving will be made as their both the same type of vehicle.
Hopefully the Durham to Newcastle section will get a hourly trial on a Sunday too if the above thing happens.
Unless the X21 was introduced to run beyond Durham on evenings and Sunday's, I would imagine Angel's would continue to do the 21/X21 as it's probably less confusing having Angel's on the X21 between Bishop Auckland and Durham than having Castles Express StreetDeck's on the 21 between Durham and Newcastle as people seeing Castle Express branded buses on the 21 may confuse people into thinking it's the limited stop X21 rather than the 21.
With any luck, if the 21 gets StreetDeck's they will hopefully be the same, or near as same specification as the examples on the X21.