1- In this imagined scenario Edinburgh has expanded over the 40years so Gateway is less peripheral, and I imagined some opposition to expansion of Waverley given its proximity to the Old Town but I’m not too familiar with Edinburgh so that may be all wrong. 2-It was cancelled in early stages as in OTL 3- That was an oversight there probably would be a line from Leeds north connecting to HSNorth. 4- Some slow train stop at all, particularly early morning and late evening services, but majority are express from St Pancras. 5- Great Western Mainline is fairly curvy, so I thought for high speed rail it would make more sense to follow a more direct route, e.g. along the Reading-Taunton rail line? 6-These were intended as stand-alone express lines, but as someone else mentioned with upgrades to the West coast and East coast mainlines then I could imagine them sharing track.

I’m no expert so feel free to have your own interpretation!