(29 Dec 2019, 11:44 am)Jimmi wrote Think at that point were it was 10 minutes across the whole route (Newcastle to Durham), I remember the reliability being poor at best, was forever running in twos into Durham and gaps of buses not turning up. Have to agree on the Chester to Toon section needing to be kept frequent as it's rather busy.

Yes it was 10 minutes between Newcastle and Durham, as they also increased the frequency of the then 24 from Wrekenton to Newcastle to every 10 minutes. 
This created a combined every 5 minute frequency between Low Fell and Newcastle, but the problem was that many passengers along the Durham Road corridor use the services south of Low Fell where the 24 turned off to go to Wrekenton, so they lost out, and the 21 struggled to cope  with the strain put it on it south of Low Fell.