So you have
0000 London, York, Darlington, Newcastle, Berwick, Edinburgh
0030 London, Peterborough, Newark, Doncaster, York, Darlington, Durham, Alnmouth, Edinburgh (as proposed)
0100 As 0000
0130 London, Peterborough, Newark, Doncaster, York, Northallerton, Darlington, Durham, Newcastle, Dunbar, Edinburgh,
A very unusual proposal. Why does the 00:30 not call at Newcastle? Seems like a sensible place to make a call. You've managed to avoid serving Morpeth, yet Alnmouth has 2tph. Might I suggest adding a Newcastle stop to the 00:30 and a Morpeth stop to the 01:30? Leaving XC to run services stopping at all (appropriate) stations between Edinburgh and Newcastle at various points during the day.
xx:00 London, York, Darlington, Newcastle, Berwick, Edinburgh (as above)
xx:30 London, Peterborough, Newark, Doncaster, York, Darlington, Durham, Newcastle, Alnmouth, Edinburgh (as above, adding a NCL stop)
xy:00 London, York, Darlington, Newcastle, Berwick, Edinburgh (as above)
xy:30 London, Peterborough, Newark, Doncaster, York, Northallerton, Darlington, Durham, Newcastle, Morpeth, Dunbar, Edinburgh
I'd extend 2tph to the North if at all possible, to Inverness and Dundee/Aberdeen. When the wires start to go up, I'd like to see whether it would be possible to terminate some at Stirling (although I think this is more of a pipe dream from my point of view!)