"London to Stirling via Cumbernauld or as with WSMR London to Stirling via Edinburgh but not stopping at Edinburgh Waverley might be the sort of options."
Which raises all sorts of interesting questions.
The first is whether the rules could/should be changed to avoid the need for 'artificial' routes?
Are there a whole set of new cross country routes that should have direct services (or perhaps faster/more frequent ones - probably by stopping at fewer stations)?
Is there too much concentration on 'destination London'?
Would independence mean more or fewer trips to London?
With or without independence should there be more/better links with the north of England - or even the north of Scotland?
Then there's the question of encouraging (or not) more travel!
But this is 'transport' - can't expect it to be too rational.
Perhaps a greatly upgraded rail line to Inverness would be better than dualling the A9(?)
If there is any case for High Speed Rail, perhaps the first route should be (say) Salford to Stirling!?
Currently there is no shortage of transport developments in/around/to London.