Diana is a narrow gauge 0-4-0T steam locomotive. It was built by Kerr, Stuart and Company in 1909, and was delivered to the Kerry Tramway in Mid Wales, in 1917. After varied service in the Welsh slate industry, Diana was purchased by railway enthusiast Graham Mullis in 1964. After many years at a variety of location, Diana was purchased by a Talyllyn Railway volunteer in 2014, and restored to working order in 2015.