When the 21/21a/21b ran, they were what, every 10mins between Pilgrim St and Chester? The services then diverged.
Traffic hasn't really increased over the last 7 years and I can't see passenger numbers have increased in that time, to an amount whereby the 21 can't cope.
Prior to that, the 7xx series (and 231) were supplemented by the local Gateshead services, from just a few metres down the road at Worswick Street. They all had a common route on a 6/7 min frequency, before again they diverged.
Traffic may have changed slightly since then.
Why then, does the service suffer so badly now? Does the 21 need to be so frequent? Does it need to stay in its current Eldon Square - Chester/Durham guise? It can only be because the company have made a rod for their own back, by stubbornly persevering with the service over the years.
RE: Go North East: Service Suggestions
'Illegitimis non carborundum'