http://www.lynton-rail.co.uk/
At the moment it is just a short section of track down from the station and back. But there are plans to extend back towards Barnstaple to Blackmore Gate, which talking to the volunteers is likely to be completed in the next couple of years.
The Ffestinog Railway have a Manning Wardle in the style of an L&B loco that visits from tme to time, and the Baldwin loco replica is also in progress, along with some L&B coaches. Not sure if much original rolling stock survives though...