(28 Apr 2015, 8:03 pm)aureolin wrote Saturdays and Sundays are fine. It can't cope Mon-Fri daytime, and it drags on until about 7pm in the evening. I can say the same for the 0710 from Coxhoe to Durham - it's very rarely late, but I wouldn't expect it to be at that time?

I'd recommend doing the Durham to Sedgefield stretch actually Marcus. It's quite a nice trip through the outskirts of Durham.

I was a regular on the 8.15 (or as close to that as it is), south out of Durham for a good few months last summer.
It was a short run to Durham from Teesside, that usually got in early, waited and then headed back south.

Traffic into Stockton on a morning, is unpredictable. I have done it whilst driving for many years on and off. Last summer, was the first time as a regular passenger.
We could arrive into Stockton early, late, on time - there were no guarantees, regardless of getting to any point prior to Tesco on time. The arrival window into Stockton, had a range of 20mins.
Passengers were generally the same people, so loads didn't vary greatly and there were no issues with queries to the driver either.

On an afternoon/evening when heading north - I often positioned myself between the northbound stops on the top of the High Street, as anything coming out of Middlesbrough, seemed to arrive late.
If I went for an X1, the X7 would turn up. 21a, and an X10 would pull up...
It was never just limited to the X1.

The times I have used it south out of Chester on a morning, when needing to get a connecting train from Durham, have always seen a decent amount of layover on Front St, suggesting the morning peak has enough time built into it from Newcastle.

Sending it via Washington services may help, but we all know how many times the X21 is diverted off the motorway. Local knowledge may assist with Chester/Crook drivers. Dread to think where Stockton drivers will end up, apart from the obvious option of choosing Birtley.
Whilst that may solve issues at the northern end of the route, I have no idea what could be done at the southern end, in and around Stockton and Middlesbrough.