The 21 isn't an easy solve for anyone, in fact it probably can't be solved.
The 221 had the same problems and that ran Newcastle - Chester, the Classic 21 always came in bunches. There's never been a reliable on time service because its impossible.
You can't remove the traffic congestion from Birtley, Low Fell or Gateshead. No amount of route splitting or frequency change will help that.
The Angel has been alright of late but with heavy loadings and traffic even during the daytime its a losing battle
RE: Go North East - Latest