The Talyllyn Railway is a narrow-gauge preserved railway in Wales . It runs for 7.25 m from Tywyn on the Mid-Wales coast to Nant Gwernol near the village of Abergynolwyn . The Talyllyn Railway is a narrow-gauge preserved railway in Wales running for 7.25 m from Tywyn on the Mid-Wales coast to Nant Gwernol near the village of Abergynolwyn .