An interesting (which is not the same as exciting....) new service is finally starting at the end of this month, having missed a couple of deadlines. The interesting part is that once the full service is running it will give 4 direct daytime trains between Stirling (plus some station east side of Glasgow) to London Euston via the west coast mainline. Currently there is one to London Kings Cross via the east coast mainline. They also call at either Crewe or Nuneaton (which are an easy connection to Birmingham) also Preston (connecting Liverpool and Manchester). Obviously at Stirling it opens up connections futher north. It's been over 40 years since there was last a direct train on this route - and then only one per day. The benefit is that until now your options were to change trains at Haymarket in Edinburgh, which adds two sides to a triangle in journey length or go via Glasgow and change stations in the city centre.
However, there are a few niggles. There will be no 1st class, which will disappoint a lot of tourists, and catering is minimal. Worst of all, the entire route is electrified but they are starting with 20 year old diesel trains, the motors are under the floor of each car and so there is a background of noise and vibration that you don't get on the electric trains. Whether they will all be refurbished like those in the publicity in time to begin work remains to be seen.
The company is called Lumo, and is not part of the privatised (and soon to be renationalised) fragmented ex British Rail majority of train operating companies - but they are integrated in the National Rail ticketing system. https://www.lumo.co.uk/where-we-go/stirling tickets should be available via all the usual suspects plus the Lumo website/app (which will sell other operators as well).
They already run some less imaginative services on the east coast mainline and because of the fare integration they accept Eurail / Britrail passes - now you see why it's interesting!