There used to be two main railway lines to Plymouth from the East - the Great Western routes via Taunton, Exeter, the sea wall at Dawlish and Totnes, and the London and South Western Route, via Salisbury, Exeter, Okehampton, the flank of Dartmoor, and Tavistock.
Alas - the South Western route was severed in 1968, and there's no track now from Meldon Quarry, via Tavistock to Bere Alston. And the section from Yeoford Junction to Okehampton has a very limited (Summer Sunday only) service ...
40 years ago, the world was a very different place. And there are many who wish that what might have been a sensible economy move in those day could easily be reversed. There are some good reasons - the following have been quoted:
1. Commuter traffic in and out of Exeter from Okehampton.
2. Commuter traffic from a rapidly growing Tavistock to Plymouth.
3. The provision of an alternative route to the sea wall via Dawlish, where global warning, rising sea levels and changing weather are making the route more prone to closure now and into the future.
4. The provision of extra capacity to Plymouth on a rail network where passenger numbers are strongly increasing.
The picture at the top of the pages of this site for September is of a First Great Western train at Okehampton station during this summer's service - my thanks to reflex109 for permission to reproduce it here.
Tavistock:
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=804.0Okehampton:
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=2338.0Sea Wall:
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=3146.0