(19 Aug 2025, 6:01 pm)DodgepotMcDougal wrote The problem with the X10 is the likely yield per passenger.

It's mostly concessions from what I've seen. Fare payers from Middlesbrough, Stockton and Billingham have deserted it for the improved Northern service. 

Maybe it just needs to be Peterlee to Newcastle every 30 minutes with an hourly extension to Middlesbrough? Maybe even missing out Billingham entirely to speed up trips

Think you've used the key phrase there. 'Improved'.
Twice hourly and more chance of a seat/less chance of a breakdown/delay and if there is a breakdown/delay - then there's the delay repay scheme.