tbtc
Veteran Member
To make any significant time savings between London and Edinburgh, you basically need to new alignments. The first from Northallerton to Birtley (avoiding Darlington and Durham), and the second from Cramlington to West Chevington (avoiding Morpeth, Pegswood and Widdrington)
This would also allow for a revival of "local" services on the ECML. At the moment there are a few stations that don't have a decent service because of the need to path "fast" trains.
For example, if you are in Alnwick and wanting to visit the next town down the line, if you miss the 07:59 from Alnmouth to Morpeth the next train is 17:01. Going northbound, if you miss the 06:40 from Morpeth, the next train to Alnmouth isn't till 17:36. Berwick lacks decent service to Alnmouth and Morpeth too (since trains tend to "skip stop", so only serve one of the places in Northumberland). Fair enough if you only want to travel from these Northumberland towns to Newcastle (or Edinburgh), but local demand has to be met by driving along the single carriageway A1 instead.
Even if you don't re-open branches to Blyth etc, I could imagine Newcastle - Cramlington - Morpeth could justify a few local trains an hour (maybe an hourly extension to Alnmouth too?).
Diverting fast trains away from Durham would allow Chester le Street to get a good level of service for the first time I can remember (a decent catchment area, though only one train an hour will never realise this), plus there'd be space on the ECML for some Middlesbrough - Durham - Newcastle services (faster than the Sunderland route, though there's no space for them at the moment).
Same goes with Dunbar/ Mussleburgh etc having relatively poor services to Edinburgh, because fast trains are more of a priority (and there's little space for local ones).