I read a most interesting article recently, by a timetable expert, on the proposal to add direct services to/from Sunderland on the ECML to Kings Cross. Basically, he was saying that the Office of the Rail Regulator (ORR) which was supporting the proposal, didn’t have a clue about what they were doing. They had, he suggested, no understanding of the true complexity of the existing timetable, born of historical demands and compromises, and should await a total recasting of it before recommending additional access for a possible fly-by-night (interesting concept!) new operator. An additional point was that this would prevent GNER enhancing their Leeds services, an important of their business plan when renewing the franchise last year.
What is needed, he suggests, is a proper regular interval timetable like the Swiss model. (Southern Electric has been running a version of this for about 60 years too, and a lot of German railways run this way - why can’t the British rail network ? [I'll tell you - the stupidity of rail privatisation]).