Also Buchanan Street has a connection to Queen Street, although there are no direct services to London from there either.
In fairness, I don't think there are any stations in Scotland where you can't get to London either directly or with one change - mostly due to the Sleeper network. (Although the frequencies are often low and many journeys would necessitate multiple changes). However, if we disallow the walk between Central and Queen Street then I'd nominate:
- Ashfield, Possilpark & Parkhouse, Gilshochill, Summerston, Maryhill
- Springburn, Duke Street, Alexandra Parade, Barnhill, Stepps, Gartcosh
- Bishopbriggs if going to London (although you can get from London with a change at Edinburgh if and only if you connect onto the 2300 departure from EDB).
(I was going to include Lenzie as well, but there is a service to Edinburgh just once a day).
However, in reality, passengers from these stations going South would walk across Glasgow to catch a train to London.